func_code_string: #include <bits/stdc++.h>   int a, b, c, d, n;   char s[4 << 20];   void output() {     for (int i = 0; i < n; ++i)       if (s[i] ==  4 )         a--;       else         b--;     for (int i = 0; i < n; ++i)       if (s[i] ==  4 ) {         while (a) {           printf( 4 );           a--;         }         printf( 4 );       } else {         while ((i + 2 >= n) && b) {           printf( 7 );           b--;         }         printf( 7 );       }     printf(  n );     exit(0);   }   void look(char c4, char c7, int a, int b, int c, int d) {     n = 0;     while (c) {       if (n) d--;       s[n++] = c4;       s[n++] = c7;       a--;       b--;       c--;     }     if (d > 0) {       s[n++] = c4;       a--;       d--;     }     if ((a < 0) || (b < 0) || (c != 0) || (d != 0)) return;     output();   }   int main() {     scanf( %d%d%d%d , &a, &b, &c, &d);     look( 4 ,  7 , a, b, c, d);     look( 7 ,  4 , b, a, d, c);     printf( -1 n );     return 0;   }   