#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<cassert>
#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<queue>
#include<set>
#include<map>
#include<utility>
#include<numeric>
#include<algorithm>
#include<bitset>
#include<complex>
#include<stack>

using namespace std;

typedef long long Int;
typedef vector<int> vint;
typedef pair<int,int> pint;
#define mp make_pair

template<class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cout << *i << " "; cout << endl; }
template<class T> void chmin(T &t, T f) { if (t > f) t = f; }
template<class T> void chmax(T &t, T f) { if (t < f) t = f; }
int in() { int x; scanf("%d", &x); return x; }

const double EPS=1e-10;
const double INF=1e+10;
const double PI=acos(-1.0);
int sig(double r){return (r<-EPS)?-1:(r>EPS)?1:0;}
struct Pt{
	double x,y;
	Pt(){}
	Pt(double x,double y):x(x),y(y){}
	Pt operator+(const Pt &a)const{return Pt(x+a.x,y+a.y);}
	Pt operator-(const Pt &a)const{return Pt(x-a.x,y-a.y);}
	Pt operator*(const Pt &a)const{return Pt(x*a.x-y*a.y,x*a.y+y*a.x);}
	Pt operator-()const{return Pt(-x,-y);}
	Pt operator*(const double &k)const{return Pt(x*k,y*k);}
	Pt operator/(const double &k)const{return Pt(x/k,y/k);}
	double abs()const{return sqrt(x*x+y*y);}
	double abs2()const{return x*x+y*y;}
	double arg()const{return atan2(y,x);}
	double dot(const Pt &a)const{return x*a.x+y*a.y;}
	double det(const Pt &a)const{return x*a.y-y*a.x;}
	bool operator<(const Pt &a)const{return x*a.x+y*a.y;}
	bool operator==(const Pt &a)const{return (sig(x-a.x)==0&&sig(y-a.y)==0);}
};
ostream &operator<<(ostream &os,const Pt &a){os<<"("<<a.x<<", "<<a.y<<")";return os;}
double tri(Pt a,Pt b,Pt c){return (b-a).det(c-a);}
bool iLS(Pt a,Pt b,Pt c,Pt d){
	return (sig(tri(a,b,c))*sig(tri(a,b,d))<0);
}

int main() {
	int n;
	while(n=in()){
		vector<Pt> vpt;
		double x,y;
		int i,j;
		for(i=0;i<n;i++){
			scanf("%lf,%lf",&x,&y);
			vpt.push_back(Pt(x,y));
		}
		int res=n;
		for(i=0;i<n-1;i++){
			int k=0;
			for(j=i+1;j<n;j++){
				int a,b;
				for(a=0;a<n-1;a++){
				if(a==i||a==j)continue;
					for(b=a+1;b<n;b++){
						if(b==i||b==j)continue;
						if(iLS(vpt[i],vpt[j],vpt[a],vpt[b]))goto batsu;
					}
				}
				k++;
				if(k==2)break;
				batsu:;
			}
			res-=k;
		}
		cout<<res<<endl;
	}
	return 0;
}