func_code_string: #include <bits/stdc++.h>   using namespace std;   inline long long read() {     long long x = 0, f = 0;     char ch = getchar();     while (!isdigit(ch)) f |= (ch ==  - ), ch = getchar();     while (isdigit(ch)) x = x * 10 + ch -  0 , ch = getchar();     return f ? -x : x;   }   inline void write(long long x) {     if (x < 0) x = -x, putchar( - );     if (x >= 10) write(x / 10);     putchar(x % 10 +  0 );   }   long long n, now[4][4] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};   inline long long find(long long x, long long y) {     return (x / 4) * (n / 4) + y / 4 + 1;   }   signed main() {     n = read();     for (register long long i = 0; i <= n - 1; i++) {       for (register long long j = 0; j <= n - 1; j++) {         long long at = find(i, j);         cout << (at - 1) * 16 + now[i % 4][j % 4] <<    ;       }       puts(  );     }     return 0;   }   