IOIT airstrike - 15p

#include <bits/stdc++.h>
#define x first
#define y second

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int N;
    cin >> N;
    vector<pair<int,int>> a(N);
    for(auto &x : a)
        cin >> x.x >> x.y;
    vector<bool> mark(N);
    int ans = 0, erased = 0;
    while(erased < N) {
        ++ans;
        vector<int> cntX(N + 1), cntY(N + 1);
        int mx = 0, type = 1, v = 0;
        for(int i = 0; i < N; ++i)
            if(!mark[i]) {
                ++cntX[a[i].x], ++cntY[a[i].y];
                if(cntX[a[i].x] > mx) {
                    mx = cntX[a[i].x];
                    type = 1;
                    v = a[i].x;
                }
                if(cntY[a[i].y] > mx) {
                    mx = cntY[a[i].y];
                    type = 0;
                    v = a[i].y;
                }
            }
        if(type == 1) {
            for(int i = 0; i < N; ++i)
                if(!mark[i] && a[i].x == v) {
                    mark[i] = true;
                    ++erased;
                }
        }
        else
            for(int i = 0; i < N; ++i)
                if(!mark[i] && a[i].y == v) {
                    mark[i] = true;
                    ++erased;
                }
    }
    cout << ans;
}