#include <stdio.h>

int n;
int *x, *y, *p;
int h, nh;

int hladaj(int h)
{
  int s = 0, t, i;
  
  t = h;
  for (i = 0; i < n; i++)
    p[i] = 0;
  
  do
  {
    i = 0;
    while (i < n) {
    if ((p[i] == 0) && (y[i] == y[t]) && (x[i] > x[t]))
    {
      s += x[i] - x[t];
      p[i] = 1;
      t = i;
      i = 0;
    } else i++; }

    i = 0;
    while (i < n) {
    if ((p[i] == 0) && (x[i] == x[t]) && (y[i] < y[t]))
    {
      s += y[t] - y[i];
      p[i] = 1;
      t = i;
      i = 0;
    } else i++; }

    i = 0;
    while (i < n) {
    if ((p[i] == 0) && (y[i] == y[t]) && (x[i] < x[t]))
    {
      s += x[t] - x[i];
      p[i] = 1;
      t = i;
      i = 0;
    } else i++; }

    i = 0;
    while (i < n) {
    if ((p[i] == 0) && (x[i] == x[t]) && (y[i] > y[t]))
    {
      s += y[i] - y[t];
      p[i] = 1;
      t = i;
      i = 0;
    } else i++; }
  } while (t != h);

  return s;
}

int main()
{
  int i, c;
  scanf("%d", &n);
  while (n)
  {
    x = new int[n];
    y = new int[n];
    p = new int[n];
    
    h = 0;
    for (i = 0; i < n; i++)
    {
      scanf("%d%d", x + i, y + i);
      p[i] = 0;
      if ((y[i] > y[h]) || ((y[i] == y[h]) && (x[i] < x[h])))
        h = i;
    }
    
    p[h] = 1;
    c = hladaj(h);
    printf("The length of the fence will be %d units.\n", c);
    
    delete x;
    delete y;
    delete p;
    scanf("%d", &n);
  }
  return 0;
}