#include <bits/stdc++.h>   const int MOD = 1e9;   const int N = 100003;   using namespace std;   vector<int> ans;   int main() {     int n;     cin >> n;     int p, q;     p = q = 0;     for (int i = 0; i < n; i++) {       char c;       int x, y;       cin >> c;       scanf( %d , &x);       scanf( %d , &y);       if (x > y) swap(x, y);       if (c ==  + )         p = max(p, x), q = max(q, y);       else if (p <= x && q <= y)         cout <<  YES ;       else         cout <<  NO ;       cout << endl;     }     return 0;   }   