#include <bits/stdc++.h> typedef long long ll ; using namespace std; vector < pair < ll , ll > > vec; ll memo[5005]; const ll inf = 1e18 ; ll solve(int i){ if(i == vec.size()) return 0 ; ll &ret = memo[i]; if(ret != -1) return ret ; ll x = vec[i].first ; ret = inf ; for(int j = i ; j < (int)vec.size() ; j++){ ret = min(ret, 4 * x * vec[j].second + solve(j + 1)); } return ret ; } int main() { ios::sync_with_stdio(false), cin.tie(0), cout.tie(0); int n ; cin >> n ; vector < pair < ll, ll > > ve; for(int i = 0 ; i < n ; i++) { ll x,y ; cin >> x >> y ; x = abs(x); y = abs(y); ve.push_back({x, y}); } sort(ve.rbegin(), ve.rend()); vector < bool > vis(n , 0); for(int i = 0 ; i < n ; i++){ for(int j = i + 1 ; j < n ; j++){ if(vis[j]) continue; if(ve[i].second < ve[j].second) break ; else vis[j] = 1; } } for(int i = 0 ; i < n ; i++){ if(!vis[i]) vec.push_back(ve[i]); } memset(memo , -1 , sizeof memo); cout << solve(0) << endl; return 0; }

cover.cpp: In function 'll solve(int)':
cover.cpp:12:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(i == vec.size()) return 0 ;
       ~~^~~~~~~~~~~~~