func_code_string: #include <bits/stdc++.h>   using namespace std;   int n;   vector<pair<pair<int, int>, int> > v;   signed main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cin >> n;     for (int i = 1; i <= n; i++) {       int x, y;       cin >> x >> y;       v.push_back(pair<pair<int, int>, int>(pair<int, int>(x / 2012, y), i));     }     sort(v.begin(), v.end());     for (int i = 0; i < v.size(); i++) cout << v[i].second <<    ;   }   