func_code_string: #include <bits/stdc++.h>   using namespace std;   int n;   inline int read() {     int x = 0, f = 1;     char ch = getchar();     while (ch <  0  || ch >  9 ) {       if (ch ==  - ) f = -1;       ch = getchar();     }     while (ch >=  0  && ch <=  9 )       x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();     return x * f;   }   inline void write(int x, char end =    ) {     char F[200];     int tmp = x > 0 ? x : -x, cnt = 0;     if (x == 0) putchar( 0 );     if (x < 0) putchar( - );     while (tmp > 0) F[cnt++] = tmp % 10 +  0 , tmp /= 10;     while (cnt > 0) putchar(F[--cnt]);     putchar(end);   }   void f(int a, int b) { write(a), write(b,   n ); }   int main() {     n = read();     if (n % 4 >= 2) return puts( NO ), 0;     puts( YES );     for (int i = 1; i < n; i += 2) {       for (int j = i + 2; j < n; j += 2)         f(i, j), f(i + 1, j + 1), f(i, j + 1), f(i + 1, j);       if (n % 4 == 1)         f(i, n), f(i, i + 1), f(i + 1, n);       else         f(i, i + 1);     }     return 0;   }   