#include <iostream>
using namespace std;
typedef long double ld;
bool hantei(ld d,ld e,ld f,ld g,ld h,ld i,ld m,ld n){
	long double x=(h-f)*(n-g)-(m-f)*(i-g);
	bool ret=x*(f-d)*(n-e)>x*(m-d)*(g-e)&&x*(d-h)*(n-i)>x*(m-h)*(e-i);
	return ret;
}
int main(){
    int n;
    cin>>n;if(n>=5){return 0;}
    if(n==1){cout<<'0'<<endl;}
    if(n==2){cout<<'1'<<endl;}
    if(n==3){cout<<'3'<<endl;}
    if(n==4){
    	long double x[4],y[4];
    	for(int j=0;j<4;j++){cin>>x[j]>>y[j];}
    	bool r1=hantei(x[0],y[0],x[1],y[1],x[2],y[2],x[3],y[3]);
    	bool r2=hantei(x[0],y[0],x[1],y[1],x[3],y[3],x[2],y[2]);
    	bool r3=hantei(x[0],y[0],x[2],y[2],x[3],y[3],x[1],y[1]);
    	bool r4=hantei(x[1],y[1],x[2],y[2],x[3],y[3],x[0],y[0]);
    	bool r5=r1|r2|r3|r4;
    	if(r5==true){cout<<'6'<<endl;}
    	else{cout<<'5'<<endl;}
    }
    return 0;
}