func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 1e6 + 5;   constexpr int SQRT = 1000;   struct query {     int x, y, pos;     short sqrt;     bool operator<(const query &b) const {       if (sqrt == b.sqrt) {         return ((sqrt & 1) ^ y < b.y);       }       return sqrt < b.sqrt;     }   };   query que[MAXN];   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     int n;     cin >> n;     for (int i = 0; i < n; i++) {       cin >> que[i].x >> que[i].y;       que[i].pos = i + 1, que[i].sqrt = que[i].x / SQRT;     }     sort(que, que + n);     for (int i = 0; i < n; i++) {       cout << que[i].pos <<    ;     }     cout <<   n ;   }   