#include <iostream>
#include <string.h>

using namespace std;

int main()
{
  int x,y,n;
  unsigned long free;
  int dx, dy;

  int r[20000];
  int s[20000];
  int dxx[40000];
  int dyy[40000];
  int damx[400000];
  int damy[400000];

  int posy;

  while(cin >> x && cin >> y && cin >> n)
  {
  if(x == 0 && y == 0 && n == 0)
    break;

  free = x * y;


  int pocetRiadkov = 0;
  int pocetStlpcov = 0;
  int index = 0;
  int damindex = 0;

  for(int i = 0; i<n; i++)
  {
    bool next = true;
    cin >> dx;
    dx -= 1;
    cin >> dy;
    dy -= 1;

    //riadky
    for(int i = 0; i<pocetRiadkov; i++)
    {
        if(r[i]==dx)
        {
            next = false;
            break;
        }
    }

    if(next)
    {
        r[pocetRiadkov] = dx;
        pocetRiadkov++;
        free -= (y-(pocetStlpcov));
    }

    //stlpce
    next = true;
    for(int i = 0; i<pocetStlpcov; i++)
    {
        if(s[i]==dy)
        {
            next = false;
            break;
        }
    }
    if(next)
    {
        s[pocetStlpcov] = dy;
        pocetStlpcov++;
        free -= (x-(pocetRiadkov));
    }

    damx[damindex]=dx;
    damy[damindex]=dy;
    damindex++;
}

for(int i = 0; i<n; i++)
{
    bool next = true;
    dx = damx[i];
    dy = damy[i];

    //diagonaly
    {
        //start
        posy = dy;
        for(int i = dx; i >= 0; i--)
        {
next = true;
            if(posy < y)
            {
                //cout << "y: " << posy << endl;
                //prehrabem pole ci je zaznam
                for(int j = 0; j < index; j++)
                {
                    if(dxx[j] == i && dyy[j] == posy)
                    {
                        next = false;
                        break;
                    }
                }
                if(next)
                {
                    for(int k = 0; k<pocetRiadkov; k++)
                    {
                        if(r[k]==i)
                        {
                            next = false;
                            break;
                        }
                    }
                    if(next)
                    {
                        for(int k = 0; k<pocetStlpcov; k++)
                        {
                            if(s[k]==posy)
                            {
                                next = false;
                                break;
                            }
                        }
                    }
                }
                if(next)
                {
                    dxx[index] = i;
                    dyy[index] = posy;
                    index++;
                    free--;
                }
                posy++;
            }
            else
                break;
        }
        //end

        //start
        posy = dy;
        for(int i = dx; i < x; i++)
        {
next = true;
            if(posy >= 0)
            {
                //prehrabem pole ci je zaznam
                for(int j = 0; j < index; j++)
                {
                    if(dxx[j] == i && dyy[j] == posy)
                    {
                        next = false;
                        break;
                    }
                }
                if(next)
                {
                    for(int k = 0; k<pocetRiadkov; k++)
                    {
                        if(r[k]==i)
                        {
                            next = false;
                            break;
                        }
                    }
                    if(next)
                    {
                        for(int k = 0; k<pocetStlpcov; k++)
                        {
                            if(s[k]==posy)
                            {
                                next = false;
                                break;
                            }
                        }
                    }
                }
                if(next)
                {
                    dxx[index] = i;
                    dyy[index] = posy;
                    index++;
                    free--;
                }
                posy--;
            }
            else
                break;
        }
        //end

        //start
        posy = dy;
        for(int i = dx; i >= 0; i--)
        {
next = true;
            if(posy >=0)
            {
                //prehrabem pole ci je zaznam
                for(int j = 0; j < index; j++)
                {
                    if(dxx[j] == i && dyy[j] == posy)
                    {
                        next = false;
                        break;
                    }
                }
                if(next)
                {
                    for(int k = 0; k<pocetRiadkov; k++)
                    {
                        if(r[k]==i)
                        {
                            next = false;
                            break;
                        }
                    }
                    if(next)
                    {
                        for(int k = 0; k<pocetStlpcov; k++)
                        {
                            if(s[k]==posy)
                            {
                                next = false;
                                break;
                            }
                        }
                    }
                }
                if(next)
                {
                    dxx[index] = i;
                    dyy[index] = posy;
                    index++;
                    free--;
                }
                posy--;
            }
            else
                break;
        }
        //end

        //start
        posy = dy;
        for(int i = dx; i < x; i++)
        {
next = true;
            if(posy < y)
            {
                //prehrabem pole ci je zaznam
                for(int j = 0; j < index; j++)
                {
                    if(dxx[j] == i && dyy[j] == posy)
                    {
                        next = false;
                        break;
                    }
                }
                if(next)
                {
                    for(int k = 0; k<pocetRiadkov; k++)
                    {
                        if(r[k]==i)
                        {
                            next = false;
                            break;
                        }
                    }
                    if(next)
                    {
                        for(int k = 0; k<pocetStlpcov; k++)
                        {
                            if(s[k]==posy)
                            {
                                next = false;
                                break;
                            }
                        }
                    }
                }
                if(next)
                {
                    dxx[index] = i;
                    dyy[index] = posy;
                    index++;
                    free--;
                }
                posy++;
            }
            else
                break;
        }
        //end

    }

  }

  cout << free << endl;

/*
  cout << endl << "r" << endl;
  for(int i = 0; i<pocetRiadkov; i++)
     cout << r[i] << " ";
  cout << endl << "s" << endl;
  for(int i = 0; i<pocetStlpcov; i++)
     cout << s[i] << " ";
  cout << endl << "dxx" << endl;
  for(int i = 0; i<index; i++)
     cout <<  dxx[i] << " ";
  cout << endl << "dyy" << endl;
  for(int i = 0; i<index; i++)
     cout << dyy[i] << " ";
*/
}
  return 0;
}