#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include <math.h>
#include <map>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <stack>
#include <algorithm>
#include <array>
#include <unordered_set>
#include <unordered_map>
#include <string>
using namespace std;

bool rcmp(int a, int b) { return a>b; }
typedef long long LL;

typedef struct { int x, y; } Point;

char inseg(Point a, Point b, Point c) {
    LL dx1=a.x-b.x;
    LL dy1=a.y-b.y;
    LL dx2=c.x-b.x;
    LL dy2=c.y-b.y;
    LL dd = dx1*dy2-dy1*dx2;
    if (dd) return 0;
    if ((c.x-a.x)*(c.x-b.x)<=0&&(c.y-a.y)*(c.y-b.y)<=0) return 1;
    return 0;
}

char cross(Point a, Point b, Point c, Point d) {
    LL dx1=a.x-b.x;
    LL dy1=a.y-b.y;
    LL dx2=c.x-b.x;
    LL dy2=c.y-b.y;
    LL dd = dx1*dy2-dy1*dx2;
    if (dd==0) {
        if ((c.x-a.x)*(b.x-a.x)>=0 && (c.y-a.y)*(b.y-a.y)>=0) return 1;
        // no care for reverse
        return 0;
    }
    LL dx=d.x-c.x;
    LL dy=d.y-c.y;
    // (c.y+k*dy-b.y)*(a.x-b.x) = (a.y-b.y)*(c.x+k*dx-b.x)
    LL va = (a.x-b.x)*dy-(a.y-b.y)*dx;
    if (va==0) return 0;
    LL vb = (a.y-b.y)*(c.x-b.x)-(a.x-b.x)*(c.y-b.y);
    if (va<0) vb=-vb;
    if (vb>0) return 0;

    dx=a.x-b.x;
    dy=a.y-b.y;
    // (b.y+k*dy-d.y)*(c.x-d.x) = (c.y-d.y)*(b.x+k*dx-d.x)
    va = (c.x-d.x)*dy-(c.y-d.y)*dx;
    if (va==0) return 0;
    vb = (c.y-d.y)*(b.x-d.x)-(c.x-d.x)*(b.y-d.y);
    if (va<0) vb=-vb;
    if (vb>0) return 0;
    return 1;
}

Point pp[16];
char dp[1<<12][13][12];
int mk[12][12];
char ck[12][12][12][12];
int gn;
char dfs(int m, int s, int e) {
    if (m==0) return 0;
    if (dp[m][s][e]==-2) return gn+1;
    if (dp[m][s][e]!=-1) return dp[m][s][e];
    dp[m][s][e]=-2;
    char r = gn, t;
    int i, j;
    if (s==gn) {
        for (i=0; i<gn; i++) if ((1<<i)&m) {
            for (j=0; j<gn; j++) if (j!=i) {
                t=dfs(m&mk[i][j], i, j)+1; r=min(r, t);
            }
        }
    } else {
        for (i=0; i<gn; i++) if ((1<<i)&m) {
            if (i!=e) {
                t=dfs(m&mk[e][i], e, i)+1; r=min(r, t);
                t=dfs(m&(~(1<<i)), gn, i)+1; r=min(r, t);
            }
            for (j=0; j<gn; j++) if (j!=i && ck[s][e][i][j]) {
                t=dfs(m&mk[i][j], i, j)+1; r=min(r, t);
            }
        }
    }
    dp[m][s][e]=r;
    return r;
}
int main() {
    int n, i, j, k, m, i1, j1, mm, r;
    scanf("%d", &n);
    if (n==1) { printf("1\n"); return 0; }
    mm=(1<<n)-1;
    for (i=0; i<n; i++) scanf("%d %d", &pp[i].x,&pp[i].y);
    for (i=0; i<n; i++) for (j=i+1; j<n; j++) {
        m=0; for (k=0; k<n; k++) {
            if (k==i||k==j) m|=(1<<k);
            else if (inseg(pp[i], pp[j], pp[k])) m|=(1<<k);
        }
        m=mm&(~m);
        mk[i][j]=mk[j][i]=m;
    }
    memset(dp, 0xff, sizeof(dp));
    for (i=0; i<n; i++) for (j=0; j<n; j++) {
        for (i1=0; i1<n; i1++) for (j1=0; j1<n; j1++) {
            ck[i][j][i1][j1]=cross(pp[i], pp[j], pp[i1], pp[j1]);
            // if (ck[i][j][i1][j1]) printf("fit %d,%d  %d,%d\n", i, j, i1, j1);
        }
    }
    r=n+1; gn=n;
    for (i=0; i<n; i++) for (j=0; j<n; j++) if (i!=j) {
        // printf("try %d,%d %x\n", i, j, mk[i][j]);
        r=min(r, 1+dfs(mk[i][j], i, j));
    }
    printf("%d\n", r);

    return 0;
}