#include<bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
template <class T>
using pq = priority_queue<T>;
template <class T>
using qp = priority_queue<T, vector<T>, greater<T>>;
#define vec(T, A, ...) vector<T> A(__VA_ARGS__);
#define vvec(T, A, h, ...) vector<vector<T>> A(h, vector<T>(__VA_ARGS__));
#define vvvec(T, A, h1, h2, ...) vector<vector<vector<T>>> A(h1, vector<vector<T>>(h2, vector<T>(__VA_ARGS__)));

#define endl "\n"
#define spa ' '
#define len(A) A.size()
#define all(A) begin(A), end(A)

#define fori1(a) for(ll _ = 0; _ < (a); _++)
#define fori2(i, a) for(ll i = 0; i < (a); i++)
#define fori3(i, a, b) for(ll i = (a); i < (b); i++)
#define fori4(i, a, b, c) for(ll i = (a); ((c) > 0 || i > (b)) && ((c) < 0 || i < (b)); i += (c))
#define overload4(a, b, c, d, e, ...) e
#define fori(...) overload4(__VA_ARGS__, fori4, fori3, fori2, fori1)(__VA_ARGS__)

#define INT(...) int __VA_ARGS__; inp(__VA_ARGS__);
#define LL(...) ll __VA_ARGS__; inp(__VA_ARGS__);
#define STRING(...) string __VA_ARGS__; inp(__VA_ARGS__);
#define CHAR(...) char __VA_ARGS__; inp(__VA_ARGS__);
#define VEC(T, A, n) vector<T> A(n); inp(A);
#define VVEC(T, A, n, m) vector<vector<T>> A(n, vector<T>(m)); inp(A);

const ll MOD1 = 1000000007;
const ll MOD9 = 998244353;

template<class T> auto min(const T& a){
    return *min_element(all(a));
}
template<class T> auto max(const T& a){
    return *max_element(all(a));
}
template <class T, class S>
inline bool chmax(T &a, const S &b) {
  return (a < b ? a = b, 1 : 0);
}
template <class T, class S>
inline bool chmin(T &a, const S &b) {
  return (a > b ? a = b, 1 : 0);
}

void print(){cout << endl;}
template <class Head, class... Tail>
void print(Head &&head, Tail &&... tail) {
    cout << head;
    if (sizeof...(Tail)) cout << spa;
    print(forward<Tail>(tail)...);
}
template<typename T>
void print(vector<T> &A){
    int n = A.size();
    for(int i = 0; i < n; i++){
        cout << A[i];
        if(i == n - 1) cout << endl;
        else cout << spa;
    }
}
template<typename T>
void print(vector<vector<T>> &A){
    for(auto &row: A) print(row);
}
template<typename T, typename S>
void print(pair<T, S> &A){
    cout << A.first << spa << A.second << endl;
}
template<typename T, typename S>
void prisep(vector<T> &A, S sep){
    int n = A.size();
    for(int i = 0; i < n; i++){
        cout << A[i];
        if(i == n - 1) cout << endl;
        else cout << sep;
    }
}
template<typename T, typename S>
void priend(T A, S end){
    cout << A << end;
}
template<typename T>
void priend(T A){
    priend(A, spa);
}
template<class... T>
void inp(T&... a){
    (cin >> ... >> a);
}
template<typename T>
void inp(vector<T> &A){
    for(auto &a:A) cin >> a;
}
template<typename T>
void inp(vector<vector<T>> &A){
    for(auto &row:A) inp(row);
}
template<typename T, typename S>
void inp(pair<T, S> &A){
    inp(A.first, A.second);
}
template<typename T, typename S>
void inp(vector<pair<T, S>> &A){
    for(auto &row: A) inp(row.first, row.second);
}

template<typename T>
T sum(vector<T> &A){
    T tot = 0;
    for(auto a:A) tot += a;
    return tot;
}

void solve(){
    INT(n);
    vector<pair<ll, ll>> point(n);
    if(n <= 2){
        print(1);
        return;
    }
    inp(point);
    const ll inf = 1LL << 60;
    auto f=[&](int bit, int i, int j, int k, int t){
        return (((bit * n + i) * n + j) * n + k) * 2 + t;
    };

    vec(ll, dp, (1 << n) * n * n * n * 2, inf);

    auto dot=[&](pair<ll, ll> d1, pair<ll, ll> d2){
        return d1.first * d2.first + d1.second * d2.second;
    };

    auto cross=[&](pair<ll, ll> d1, pair<ll, ll> d2){
        return d1.first * d2.second - d1.second * d2.first;
    };

    auto line3=[&](int i, int j, int k){
        if(i == j) return true;
        ll dx1 = point[j].first - point[i].first;
        ll dy1 = point[j].second - point[i].second;
        ll dx2 = point[k].first - point[i].first;
        ll dy2 = point[k].second - point[i].second;
        pair<ll, ll> d1 = {dx1, dy1};
        pair<ll, ll> d2 = {dx2, dy2};
        if(cross(d1, d2) != 0) return false;
        if(dot(d1, d2) < 0) return false;
        return dx1 * dx1 + dy1 * dy1 < dx2 * dx2 + dy2 * dy2;
    };

    fori(bit, 1, 1 << n){
        vec(int, ind, 0);
        int pc = 0;
        fori(i, n){
            if((bit >> i) & 1){
                pc++;
                ind.push_back(i);
            }
        }
        if(pc == 1){
            int i = ind[0];
            dp[f(bit, i, i, i, 0)] = 1;
            dp[f(bit, i, i, i, 1)] = 1;
            continue;
        }
        else if(pc == 2){
            int i = ind[0];
            int j = ind[1];
            dp[f(bit, i, i, j, 0)] = 1;
            dp[f(bit, i, i, j, 1)] = 1;
            continue;
        }
        for(auto i:ind) for(auto j:ind){
            for(auto k:ind){
                if(i == k || j == k) continue;
                for(auto l:ind){
                    if(i == l || j == l || k == l) continue;
                    if(line3(i, j, k)){
                        if(line3(j, k, l)){
                            chmin(dp[f(bit, j, k, l, 1)], dp[f((bit) ^ (1 << l), i, j, k, 1)]);
                            chmin(dp[f(bit, j, k, l, 1)], dp[f((bit) ^ (1 << l), i, j, k, 0)]);
                        }
                        else{
                            chmin(dp[f(bit, j, k, l, 1)], dp[f((bit) ^ (1 << l), i, j, k, 1)] + 1);
                            chmin(dp[f(bit, j, k, l, 0)], dp[f((bit) ^ (1 << l), i, j, k, 1)] + 1);
                        }
                    }
                    else if(line3(j, k, l)){
                        chmin(dp[f(bit, j, k, l, 1)], dp[f((bit) ^ (1 << l), i, j, k, 1)]);
                        chmin(dp[f(bit, j, k, l, 1)], dp[f((bit) ^ (1 << l), i, j, k, 0)]);
                    }
                    else{
                        ll ji1 = point[j].first - point[i].first;
                        ll ji2 = point[j].second - point[i].second;
                        ll lk1 = point[l].first - point[k].first;
                        ll lk2 = point[l].second - point[k].second;
                        ll kj1 = point[k].first - point[j].first;
                        ll kj2 = point[k].second - point[j].second;
                        ll add = 0;
                        if(cross({ji1, ji2}, {lk1, lk2}) == 0) add = 1;
                        
                        ll kji = cross({ji1, ji2}, {kj1, kj2});
                        ll lkj = cross({kj1, kj2}, {lk1, lk2});
                        if(kji * lkj <= 0) add = 1;

                        ll lqk = cross({ji1, ji2}, {lk1 - ji1, lk2 - ji2});
                        if(kji * lqk <= 0) add = 1;

                        chmin(dp[f(bit, j, k, l, 0)], dp[f((bit) ^ (1 << l), i, j, k, 0)] + 1);
                        chmin(dp[f(bit, j, k, l, 0)], dp[f((bit) ^ (1 << l), i, j, k, 1)] + 1);
                        chmin(dp[f(bit, j, k, l, 1)], dp[f((bit) ^ (1 << l), i, j, k, 0)] + add);
                    } 
                }
            }
        }
    }
    ll ans = inf;
    fori(i, n) fori(j, n) fori(k, n){
        chmin(ans, dp[f((1 << n) - 1, i, j, k, 0)]);
        chmin(ans, dp[f((1 << n) - 1, i, j, k, 1)]);
    }
    print(ans);
}

int main(){
    cin.tie(0)->sync_with_stdio(0);
    int t;
    t = 1;
    // cin >> t;
    while(t--) solve();
    return 0;
}