#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cctype>

#include <iostream>
#include <sstream>
#include <string>

#include <vector>
#include <list>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <algorithm>
using namespace std;

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define FOR2(i,a,b) for (int i = (a); i > (b); --i)
/*
#define FOR(i,n) for(int i=0; i < (n); i++)
#define FORD(i,n) for(int i=(n)-1; i >= 0; i--)
#define FORTO(i,a,b) for (int i = (a); i <= (b); ++i)
*/


#define DEBUG(x) cout << '>' << #x << ' ' << x << endl;
#define SIZE(x) int(x.size())

typedef pair<int, int> PII;
typedef long long ll;

const int MAX = 147;
int N;

double xs[MAX], ys[MAX];

inline bool EQ(double a, double b) { return fabs(a-b) < 1e-9; }

struct point
{
	double x, y;
	
	point(): x(0), y(0) { }
	point(double xx, double yy): x(xx), y(yy) { }
	
	bool operator<(const point & p) const
	{
		return x < p.x || (x == p.x && y < p.y);
	}
	
	bool operator==(const point & p) const
	{
		return x == p.x && y == p.y;
	}
};

struct line
{
	point p1, p2;
	double get_y(double x)
	{
		return p1.y + (p2.y-p1.y)*(x-p1.x)/(p2.x-p1.x);
	}
} lines[MAX];

int overlap(pair<int, int> a, pair<int, int> b)
{
	if (a.second < a.first || b.second < b.first) return 0;
	int m = max(a.first, b.first), M = min(a.second, b.second);	
	return max(0, M-m);
}

int main()
{
	while (1)
	{
		scanf("%d", &N);
		if (!N) break;
		FOR(i, 0, N) scanf("%lf%lf", &xs[i], &ys[i]);
		xs[N] = xs[0];
		ys[N] = ys[0];
		
		int sz = 0;
		FOR(i, 0, N)
		{
			if (xs[i] == xs[i+1]) continue;
			
			lines[sz].p1 = point(xs[i], ys[i]);
			lines[sz].p2 = point(xs[i+1], ys[i+1]);
			if (lines[sz].p2 < lines[sz].p1)
				swap(lines[sz].p1, lines[sz].p2);
			++sz;
		}
		
		//pre kazdu suradnicu
		vector<pair<int, int> > last, act;
		int res = 0;
		FOR(x, -100, 100+1)
		{
			vector<double> y;
			//prejdem zlava
			FOR(i, 0, sz)
				if (lines[i].p1.x < x && x < lines[i].p2.x)
					y.push_back(lines[i].get_y(x));
				else if (x == lines[i].p2.x)
					y.push_back(lines[i].p2.y);
			sort(y.begin(), y.end());
			
			act.clear();
			FOR(i, 0, y.size())
			{
				act.push_back(make_pair(ceil(y[i]-1e-9), floor(y[i+1]+1e-9)));
				++i;
			}
			
			FOR(i, 0, last.size())
				FOR(j, 0, act.size())
					res += overlap(last[i], act[j]);
			
			//prejdem zprava
			y.clear();
			FOR(i, 0, sz)
				if (lines[i].p1.x < x && x < lines[i].p2.x)
					y.push_back(lines[i].get_y(x));
				else if (x == lines[i].p1.x)
					y.push_back(lines[i].p1.y);
			sort(y.begin(), y.end());
			
			last.clear();
			FOR(i, 0, y.size())
			{
				last.push_back(make_pair(ceil(y[i]-1e-9), floor(y[i+1]+1e-9)));
				++i;
			}
		}
		
		printf("%d\n", res);
	}

	return 0;
}