#include <bits/stdc++.h>
using namespace std;
#define SZ(x) (int)(x.size())
#define REP(i, n) for(int i=0;i<(n);++i)
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RREP(i, n) for(int i=(int)(n)-1;i>=0;--i)
#define RFOR(i, a, b) for(int i=(int)(b)-1;i>=(a);--i)
#define ALL(a) a.begin(),a.end()
#define DUMP(x) cerr<<#x<<" = "<<(x)<<endl
#define DEBUG(x) cerr<<#x<<" = "<<(x)<<" (L"<<__LINE__<<")"<< endl;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using P = pair<int, int>;
const double eps = 1e-8;
const ll MOD = 1000000007;
const int INF = INT_MAX / 2;
const ll LINF = LLONG_MAX / 2;
template <typename T1, typename T2>
bool chmax(T1 &a, const T2 &b) {
    if (a < b) { a = b; return true; }
    return false;
}
template <typename T1, typename T2>
bool chmin(T1 &a, const T2 &b) {
    if (a > b) { a = b; return true; }
    return false;
}
template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    os << "[";
    REP(i, SZ(v)) {
        if (i) os << ", ";
        os << v[i];
    }
    return os << "]";
}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const map<T1, T2> &mp) {
    os << "{";
    int a = 0;
    for (auto &tp : mp) {
        if (a) os << ", "; a = 1;
        os << tp;
    }
    return os << "}";
}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
    os << p.first << ":" << p.second;
    return os;
}

using Real = double;
const Real PI = acos(-1);

using Point = complex<Real>;
namespace std {
    bool operator<(const Point& a, const Point& b) {
        if (a.real() == b.real()) return a.imag() < b.imag();
        return a.real() < b.real();
    }
}
struct Line {
    Point a, b;
    Line() {}
    Line(const Point& a, const Point& b) : a(a), b(b) {}
    friend ostream& operator<<(ostream& os, const Line& l) {
        return os << "[" << l.a << "," << l.b << "]";
    }
};
struct Segment : Line {
    Segment() = default;

    Segment(const Point& a, const Point& b) : Line(a, b) {}
};

inline bool eq(Real a, Real b) { return abs(b - a) < eps; }

Real radian_to_degree(Real r) {
    return r * 180.0 / PI;
}

Real degree_to_radian(Real d) {
    return d * PI / 180.0;
}

Point rotate(const Point &p, Real theta) {
    return p * polar((Real)1.0, theta);
}

Real cross(const Point& a, const Point& b) {
    return a.real() * b.imag() - a.imag() * b.real();
}

Real dot(const Point& a, const Point& b) {
    return a.real() * b.real() + a.imag() * b.imag();
}

Point projection(const Line& l, const Point& p) {
    Real A = dot(l.b - l.a, p - l.a),
            B = dot(l.a - l.b, p - l.b);
    return (A * l.b + B * l.a) / (A + B);
}

bool parallel(const Line& l1, const Line& l2) {
    return eq(cross(l1.a - l1.b, l2.a - l2.b), 0.0);
}

bool orthogonal(const Line& l1, const Line& l2) {
    return eq(dot(l1.a - l1.b, l2.a - l2.b), 0.0);
}

const int COUNTER_CLOCKWISE = 1,
        CLOCKWISE = -1,
        ONLINE_BACK = 2,
        ONLINE_FRONT = -2,
        ON_SEGMENT = 0;
int ccw(const Point& a, Point b, Point c) {
    b = b - a, c = c - a;
    if (cross(b, c) > eps) return COUNTER_CLOCKWISE;
    if (cross(b, c) < -eps) return CLOCKWISE;
    if (dot(b, c) < 0) return ONLINE_BACK;
    if (norm(b) < norm(c)) return ONLINE_FRONT;
    return ON_SEGMENT;
}

bool intersected(const Line& l, const Point& p) {
    return abs(ccw(l.a, l.b, p)) != 1;
}

bool intersected(const Segment& s, const Point& p) {
    return ccw(s.a, s.b, p) == 0;
}

bool intersected(const Line& l, const Segment& s) {
    return cross(l.b - l.a, s.a - l.a) * cross(l.b - l.a, s.b - l.a) < eps;
}

bool intersected(const Segment& s1, const Segment& s2) {
    return ccw(s1.a, s1.b, s2.a) * ccw(s1.a, s1.b, s2.b) <= 0 and
           ccw(s2.a, s2.b, s1.a) * ccw(s2.a, s2.b, s1.b) <= 0;
}

Real distance(const Line& l, const Point& p) {
    return abs(p - projection(l, p));
}

Real distance(const Segment& s, const Point& p) {
    Point r = projection(s, p);
    if (intersected(s, r)) return abs(r - p);
    return min(abs(s.a - p), abs(s.b - p));
}

Real distance(const Line &l, const Segment &s) {
    if (intersected(l, s)) return 0;
    return min(distance(l, s.a), distance(l, s.b));
}

Real distance(const Segment& s1, const Segment& s2) {
    if (intersected(s1, s2)) return 0.0;
    return min({ distance(s1, s2.a), distance(s1, s2.b),
                 distance(s2, s1.a), distance(s2, s1.b) });
}

Point crosspoint(const Line& l1, const Line& l2) {
    Real A = cross(l2.a - l1.a, l2.b - l1.a),
            B = cross(l2.b - l1.b, l2.a - l1.b);
    return (A * l1.b + B * l1.a) / (A + B);
}




int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    const int MIN = -2000, MAX = 2000;

    for (;;) {
        int n; cin >> n;
        if (n == 0) break;
        vector<Point> ps(n);
        REP(i, n) {
            double x, y; cin >> x >> y;
            ps[i] = { x, y };
        }
        vector<Segment> ss;
        REP(i, n) {
            Point p1 = ps[i], p2 = ps[(i+1) % n];
            if (eq(p1.imag(), p2.imag())) continue;
            if (p1.imag() > p2.imag()) {
                swap(p1, p2);
            }
            ss.emplace_back(p1, p2);
        }

        int ans = 0;

        FOR(y, MIN, MAX) {
            vector<double> low, high;
            for (Segment &s : ss) {
                if (s.a.imag() < y + eps and y + 1 < s.b.imag() + eps) {
                    low.push_back(crosspoint(s, Segment{{MIN, (double)y}, {MAX, (double)y}}).real());
                    high.push_back(crosspoint(s, Segment{{MIN, (double)y+1}, {MAX, (double)y+1}}).real());
                }
            }
            //DEBUG(y);
            //DEBUG(low);
            //DEBUG(high);
            int m = low.size();
            vi ord(m);
            iota(ALL(ord), 0);
            sort(ALL(ord), [&](int i,int j){
                if (low[i] == low[j]) return high[i] < high[j];
                return low[i] < low[j]; });
            //DEBUG(ord);

            int prev = -1;
            int sum = 0;
            int xr = MIN-1;
            REP(i, m) {
                int id = ord[i];
                if (i & 1) {
                    int x = (int)(max(low[id], high[id]) + MAX - eps) - MAX;
                    //DEBUG(x);
                    sum += x - prev + 1;
                    xr = x + 1;
                } else {
                    int x = (int)(min(low[id], high[id]) + MAX + eps) - MAX;
                    //DEBUG(x);
                    prev = max(x, xr);
                    //prev = x;
                }
            }
            //DEBUG(sum);
            //cerr << endl;
            ans += sum;
        }

        cout << ans << endl;
    }
}




Measured memory_bytes: 3232