End of the Line CP101

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define pb push_back
#define p_b pop_back
#define si stack<int>
#define sll stack<ll>
#define sc stack<char>
#define vi vector<int>
#define vll vector<ll>
#define mii map<int, int>
#define msi map<string, int>
#define mci map<char, int>
#define qc queue<char>
#define qi queue<int>
#define qll queue<ll>
using namespace std;

int hcf(int a, int b){
    int rem = 1;
    while(true){
        rem = a%b;
        if(rem == 0){
            break;
        }

        a = b;
        b = rem;
    }

    return b;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin >> t;
    vector<pair<ll, ll>> v;
    while(t--){
        ll m, c;
        cin >> m >> c;
        v.pb({m, c});
    }

    ll count = 0;
    set<pair<string, string>> s;
    for(int i = 0; i < v.size()-1; i++){
        for(int j = i+1; j < v.size(); j++){
            int m1 = v[i].first, c1 = v[i].second, m2 = v[j].first, c2 = v[j].second;
            if(m1 != m2){
                string x, y;
                x = to_string(abs((c2-c1)/hcf(c1-c2, m1-m2)))+'/'+to_string(abs((m1-m2)/hcf(c1-c2, m1-m2)));
                y = to_string(abs((m1*c2-m2*c1)/hcf(m1*c2-m2*c1, m1-m2)))+'/'+to_string(abs((m1-m2)/hcf(m1*c2-m2*c1, m1-m2)));

                if((c1-c2 < 0 && m1-m2 > 0) || (c1-c2 > 0 && m1-m2 < 0)){
                    x = '-'+x;
                }

                if((m1*c2-m2*c1 < 0 && m1-m2 > 0) || (m1*c2-m2*c1 > 0 && m1-m2 < 0)){
                    y = '-'+y;
                }


                if(c2-c1 == 0){
                    x = "0";
                }

                if(m1*c2-m2*c1 == 0){
                    y = "0";
                }
                s.insert({x, y});
            }
        }
    }

    cout << s.size() << "\n";
    return 0;
}