#include<iostream>
#include <fstream>
#include<vector>
#include<cmath>
#include<queue>
using namespace std;
bool dali=0;
long long s,k,otg=0,ol1,ol2,ol3,oll;
vector<pair<long long,long long> >a;
priority_queue<long long>P;
long long n;
long long ol(long long ax,long long ay,long long bx,long long by,long long cx,long long cy){
    //cout<<(bx-ax)*(cy-ay)-(by-ay)*(cx-ax)<<" ";
    return (bx-ax)*(cy-ay)-(by-ay)*(cx-ax);
}
bool proveri(long long a1,long long b1,long long c1){
    oll=ol(a[a1].first,a[a1].second,a[b1].first,a[b1].second,a[c1].first,a[c1].second);
    if(abs(oll)<otg or dali==false){
    ol1=ol(a[a1].first,a[a1].second,a[b1].first,a[b1].second,0,0);
    ol2=ol(a[a1].first,a[a1].second,0,0,a[c1].first,a[c1].second);
    ol3=ol(a[c1].first,a[c1].second,0,0,a[b1].first,a[b1].second);
if((ol1>0 and ol2>0 and ol3>0) or (ol1<0 and ol2<0 and ol3<0)){
if(dali==false or abs(oll)<otg){
dali=true;
otg=abs(oll);
return 1;
}
}
if((ol1>0 and ol2>0 and ol3>0) or (ol1<0 and ol2<0 and ol3<0)){

}

}
return 0;
}
int main(){
cin>>n;
for(long long i=0;i<n;i++){
    //cin>>ol1>>ol2;
    a.push_back(make_pair(ol1,ol2));
}
for(long long i=0;i<n;i++){
    for(long long r=i+1;r<n;r++){
        for(long long t=r+1;t<n;t++){
                otg++;
            //proveri(i,r,t);
        }
    }
}
cout<<otg;
return 0;
}