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input/code.cpp: In function 'int main()':
input/code.cpp:27:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < v.size(); i++) {
                    ^
input/code.cpp:28:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < v.size(); j++) {
                     ^

#include <iostream>
#include <algorithm>
#include <vector>
#define ll long long

using namespace std;

bool s(pair<ll, ll> a, pair<ll, ll> b) {

	ll cross = (a.first * b.second) - (b.first * a.second);
	return (cross == 0);

}

int main() {

	vector<pair<ll, ll>> v;
	int n, ux, uy, x, y;

	cin >> n >> ux >> uy;

	for (int i = 0; i < n; i++) {
		cin >> x >> y;
		v.push_back(make_pair(x - ux, y - uy));
	}

	for (int i = 0; i < v.size(); i++) {
		for (int j = 0; j < v.size(); j++) {
			if (v[i] == v[j]) continue;
			if (s(v[i], v[j])) {
				//cout << v[i].first << " " << v[i].second;
				//cout << " on samalla linjalla kuin ";
				//cout << v[j].first << " " << v[j].second << endl;
				v.erase(v.begin() + j);
			}
		}
	}

	cout << v.size() << endl;


}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED