func_code_string: #include <bits/stdc++.h>   using namespace std;   int getint() {     unsigned int c;     int x = 0;     while (((c = getchar()) -  0 ) >= 10) {       if (c ==  - ) return -getint();       if (!~c) exit(0);     }     do {       x = (x << 3) + (x << 1) + (c -  0 );     } while (((c = getchar()) -  0 ) < 10);     return x;   }   int getc_str(char str[]) {     unsigned int c, n = 0;     while ((c = getchar()) <=    )       ;     if (!~c) exit(0);     do {       str[n++] = c;     } while ((c = getchar()) >    );     str[n] =   0 ;     return n;   }   char in[100];   int main() {     int i, j, tcc, tc = 1 << 28;     for (tcc = 0; tcc < tc; tcc++) {       int n = getint();       getc_str(in);       bool ok = 1;       for (i = 0; i < n; i++) {         if (in[i] !=  4  and in[i] !=  7 ) ok = 0;       }       int firstSum = 0, secondSum = 0;       for (i = 0; i < n / 2; i++) firstSum += in[i];       for (i = 0; i < n / 2; i++) secondSum += in[i + n / 2];       if (firstSum != secondSum) ok = 0;       if (ok) {         puts( YES );       } else {         puts( NO );       }     }     return 0;   }   