Hans Solo and Lazer gun.cpp

#include <bits/stdc++.h>
#include <set>

using namespace std;
#define ll long long


#define fo(i, n) for(int i = 0; i < n; i++)

const int N = 100001;
const int mod = (int)(1e9 + 7);

int main() {
	set<double> st;
	int n, x0, y0, x, y;
	cin >> n >> x0 >> y0;
	while(n--){
		cin >> x >> y;
		if(y0 - y == 0 && x0 - x == 0)
			continue;
		else if(y0 - y == 0)
			st.insert(20000.0);
		else if(x0 - x == 0)
			st.insert(30000.0);
		else
			st.insert(1.0 * (x0 - x) / (y0 - y));
	}
	cout << st.size() << endl;
}