DWITE 2006 Points on a Line

#include <iostream>
#include <utility>
using namespace std;

int n;
pair <int, int> xy[100];

int koliko_ima(int x1, int y1, int x2, int y2)
{
    int brojac=0;

    for (int i=0;i<n;i++)
        if ((x2-x1)*(xy[i].second-y2)==(xy[i].first-x2)*(y2-y1)) brojac++;

    return brojac;
}

int main()
{
    cin>>n;

    for (int i=0;i<n;i++)
    {
        cin>>xy[i].first;
        cin>>xy[i].second;
    }

    int x1,y1,x2,y2;

    for (int i=0;i<5;i++)
    {
        cin>>x1>>y1>>x2>>y2;
        cout<<koliko_ima(x1,y1,x2,y2)<<endl;
    }
    return 0;
}