#include <bits/stdc++.h>
#define _rep(i, x, y) for(int i = x; i <= y; ++i)
#define _req(i, x, y) for(int i = x; i >= y; --i)
#define _rev(i, u) for(int i = head[u]; i; i = e[i].nxt)
#define pb push_back
#define fi first
#define se second
#define mst(f, i) memset(f, i, sizeof f)
using namespace std;
#ifdef ONLINE_JUDGE
#define debug(...) 0
#else
#define debug(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)
#endif
typedef long long ll;
typedef pair<int, int> PII;
namespace fastio{
    #ifdef ONLINE_JUDGE
    char ibuf[1 << 20],*p1 = ibuf, *p2 = ibuf;
    #define get() p1 == p2 && (p2 = (p1 = ibuf) + fread(ibuf, 1, 1 << 20, stdin), p1 == p2) ? EOF : *p1++
    #else
    #define get() getchar()
    #endif
    template<typename T> inline void read(T &t){
        T x = 0, f = 1;
        char c = getchar();
        while(!isdigit(c)){
            if(c == '-') f = -f;
            c = getchar();
        }
        while(isdigit(c)) x = x * 10 + c - '0', c = getchar();
        t = x * f;
    }
    template<typename T, typename ... Args> inline void read(T &t, Args&... args){
        read(t);
        read(args...);
    }
    template<typename T> void write(T t){
        if(t < 0) putchar('-'), t = -t;
        if(t >= 10) write(t / 10);
        putchar(t % 10 + '0');
    }
    template<typename T, typename ... Args> void write(T t, Args... args){
        write(t), putchar(' '), write(args...);
    }
    template<typename T> void writeln(T t){
        write(t);
        puts("");
    }
    template<typename T> void writes(T t){
        write(t), putchar(' ');
    }
    #undef get
};
using namespace fastio;
#define multitest() int T; read(T); _rep(tCase, 1, T)
namespace Calculation{
    const ll mod = 998244353;
    ll ksm(ll p, ll h){ll base = p % mod, res = 1; while(h){if(h & 1ll) res = res * base % mod; base = base * base % mod, h >>= 1ll;} return res;}
    void dec(ll &x, ll y){x = ((x - y) % mod + mod) % mod;}
    void add(ll &x, ll y){x = (x + y) % mod;}
    void mul(ll &x, ll y){x = x * y % mod;}
    ll sub(ll x, ll y){return ((x - y) % mod + mod) % mod;}
    ll pls(ll x, ll y){return ((x + y) % mod + mod) % mod;}
    ll mult(ll x, ll y){return x * y % mod;}
}
using namespace Calculation;
const int N = 2005;
const double eps = 1e-9;
int n;
bool vis[N];
struct Vector{
    ll x, y;
    double alpha;
    int id;
    Vector(ll _x = 0, ll _y = 0){x = _x, y = _y, id = 0;}
    Vector operator+(const Vector b)const{return Vector(x + b.x, y + b.y);}
    Vector operator-(const Vector b)const{return Vector(x - b.x, y - b.y);}
    ll operator^(const Vector b)const{return x * b.y - y * b.x;}
    ll operator|(const Vector b)const{return x * b.x + y * b.y;}
    bool operator<(const Vector b)const{
        double t = alpha - b.alpha;
        if(fabsl(t) < eps) return x < b.x;
        return t < 0;
    }
}a[N], b[N];
int top, st[N];
void init(){
    sort(a + 1, a + 1 + n, [](Vector x, Vector y){return x.x == y.x ? x.y < y.y : x.x < y.x;});
    st[++top] = 1;
    _rep(i, 2, n){
        while(top >= 2 && ((a[st[top]] - a[st[top - 1]]) ^ (a[i] - a[st[top]])) <= 0) vis[st[top--]] = 0;
        st[++top] = i, vis[i] = 1;
    }
    // _rep(i, 1, top) debug("(%lld,%lld)\n", a[st[i]].x, a[st[i]].y);
    // debug("=============\n");
    int lst = top;
    _req(i, n - 1, 1){
        if(vis[i]) continue;
        while(top > lst && ((a[st[top]] - a[st[top - 1]]) ^ (a[i] - a[st[top]])) <= 0) vis[st[top--]] = 0;
        st[++top] = i, vis[i] = 1;
    }
    // _rep(i, 1, top) debug("(%lld,%lld)\n", a[st[i]].x, a[st[i]].y);
}
int main(){
    read(n);
    _rep(i, 1, n) read(a[i].x, a[i].y);
    init();
    int ans = 1;
    _rep(i, 1, n){
        if(vis[i]) continue;
        int cnt = 0;
        _rep(j, 1, n) if(j != i) b[++cnt] = a[j] - a[i], b[cnt].id = j, b[cnt].alpha = atan2((double)b[cnt].y, (double)b[cnt].x);
        sort(b + 1, b + 1 + cnt);
        int pos = 0, cur = 0;
        _rep(j, 1, cnt) if(vis[b[j].id]){pos = j; break;}
        for(int j = pos % cnt + 1; ; j = j % cnt + 1){
            if(vis[b[j].id]) ans += !cur, cur = 0;
            else cur++;
            if(j == pos) break;
        }
    }
    writeln(ans);
    return 0;
}