func_code_string: #include <bits/stdc++.h>   const int maxN = 1000000;   char in[maxN + 1];   int occ[10], instanceOfRest[7] = {8169, 8961, 8619, 6891, 8691, 9168, 8196};   int main() {     scanf( %s , in);     int s = std::strlen(in);     for (int i = 0; i < s; i++) occ[in[i] -  0 ]++;     occ[1]--, occ[6]--, occ[8]--, occ[9]--;     int powerOf10 = 1, res = 0, occOfZero = occ[0];     occ[0] = 4;     for (int i = 0; i < 10; i++) {       for (int j = 0; j < occ[i]; j++) {         res = (res + (i % 7) * powerOf10) % 7;         powerOf10 = (powerOf10 * 3) % 7;       }     }     for (int i = 9; i > 0; i--)       for (int j = 0; j < occ[i]; j++) printf( %d , i);     printf( %d , instanceOfRest[(7 - res) % 7]);     while (occOfZero--) printf( 0 );     printf(  n );     return 0;   }   