func_code_string: #include <bits/stdc++.h>   using namespace std;   const int inf = 0x3f3f3f3f;   const int N = 1E6 + 7;   int n;   int id[N], x[N], y[N];   bool cmp(int a, int b) {     if (x[a] < x[b]) return true;     if (x[a] > x[b]) return false;     if (x[a] % 2 == 1)       return y[a] < y[b];     else       return y[a] > y[b];   }   int main() {     scanf( %d , &n);     for (int i = 0; i < n; i++) {       scanf( %d %d , &x[i], &y[i]);       x[i] /= 1000;       y[i] /= 1000;       id[i] = i;     }     sort(id, id + n, cmp);     for (int i = 0; i < n; i++) {       printf( %d  , id[i] + 1);     }     return 0;   }   