제출 #889462

#제출 시각아이디문제언어결과실행 시간메모리
889462Kakarot별들과 삼각형 (IZhO11_triangle)C++98
0 / 100
1 ms348 KiB
#include <bits/stdc++.h>
#define ii unordered_map<int,int>
#define vi vector<int>
#define vii vector<pair<int,int>>
using namespace std;

void setIO() {
  cin.tie(0)->sync_with_stdio(0);
}

void solve() {
  int n,ans = 0;
  cin >> n;
  ii fx,fy;
  vi X(n),Y(n);
  for(int i = 0;i < n;++i) {
    cin >> X[i] >> Y[i];
    ++fx[X[i]];
    ++fy[Y[i]];
  }
  for(int i = 0;i < n;++i)
    ans += (fx[X[i]] == 2 && fy[Y[i]] == 2);
  cout << ans;
}

int main() {
  setIO();
  solve();
  return 0;
}
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