Codeforces Round #291 (Div. 2), problem: (B) Han Solo and Lazer Gun

#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define pii pair<int,int>
#define pli pair<long long int,int>
#define pbi pair<bool,int>
#define pob pop_back
#define all(a) a.begin(),a.end()
#define fio ios_base::sync_with_stdio(false); cin.tie(0);cout.tie(0);
#define i64 long long int
#define mem(x,y) memset(x,y,sizeof(x))
#define fill(arr,b) fill(arr, arr+sizeof(arr)/sizeof(arr[0]), b)
#define maxarr(n,arr,m) m =-1e9;for(int i=0;i<n;i++)if(arr[i]>m) m=arr[i];
#define read freopen("input.txt","r",stdin);

const double pi = acos(-1.0);
const int maxn = (i64)1e9+7;

int cnt;
map<pii,int> mp;

int main()
{
    //read;
    int n,x1,y1,x2,y2,x3,y3;
    scanf("%d%d%d",&n,&x1,&y1);
    for(int i=0;i<n;i++)
    {
        scanf("%d%d",&x2,&y2);
        bool fg=false;
        for(auto it:mp)
        {
            x3=it.first.first;
            y3=it.first.second;
            int a=x1*(y2-y3)+x2*(y3-y1)+x3*(y1-y2);
            if(a==0) {fg=true;break;}
        }
        if(!fg) {mp[{x2,y2}]=1;cnt++;}
    }
    printf("%d",cnt);
    return 0;
}