#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;

//template
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(a);i>(b);i--)
#define ALL(v) (v).begin(),(v).end()
typedef long long int ll; const int inf = 0x3fffffff; const ll INF = 0x3fffffffffffffff;
template<class T> inline bool chmax(T& a,T b){ if(a<b){a=b;return 1;}return 0; }
template<class T> inline bool chmin(T& a,T b){ if(a>b){a=b;return 1;}return 0; }
//template end

long double eps=1e-15;

int main(){
    int n; scanf("%d",&n);
    vector<long double> a;
    rep(i,0,n){
        int x,y; scanf("%d%d",&x,&y);
        if(x==0&&y==0)continue;
        long double theta=atan2l(x,y); if(theta<0)theta+=2*M_PI;
        a.push_back(theta);
    }
    sort(ALL(a)); n=a.size();
    ll ans=0; int idx=0;
    rep(i,0,n){
        if(a[i]>=M_PI)break;
        long double lim=a[i]+M_PI;
        int lb=upper_bound(ALL(a),lim+eps)-a.begin();
        idx=i+1;
        while(idx<n){
            if(a[idx]>=lim-eps)break;
            int rb=lower_bound(ALL(a),a[idx]+M_PI-eps)-a.begin();
            ans+=max(rb-lb,0); idx++;
        }
    }
    printf("%lld\n",ans);
    return 0;
}