#include<stdio.h>
int main()
{
	freopen("trapez.in","r",stdin);
	freopen("trapez.out","w",stdout);
int n,x,y,i,j,a[1001],b[1001],k,o=1,s=0,nr=0;
double p1[500500],p2[500500],aux;
scanf("%d",&n);
for(k=1;k<=n;k++){
        scanf("%d%d",&x,&y);
        a[o]=x;
        b[o]=y;
        o++;
	}
k=1;
for(i=1;i<n;i++){
	for(j=i+1;j<=n;j++){
	p2[k]=b[j]-b[i];
	p1[k]=a[j]-a[i];
	k++;
}	
}
		

printf("%d",nr);
return 0;
}