func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, t, b[100020], cnt, p, q;   char s[100020], s1[100020], s2[100020];   char chose(char x, char y) {     if (x !=  a  && y !=  a )       return  a ;     else if (x !=  b  && y !=  b )       return  b ;     else       return  c ;   }   int main() {     scanf( %d%d , &n, &t);     scanf( %s , s1);     scanf( %s , s2);     cnt = 0;     p = 0;     q = 0;     for (int i = 0; i < n; i++)       if (s1[i] != s2[i]) cnt++;     if (t < (cnt + 1) / 2) {       printf( -1 n );       return 0;     }     if (t <= cnt) {       for (int i = 0; i < n; i++) {         if (s1[i] == s2[i])           s[i] = s1[i];         else {           p++;           if (p <= 2 * t - cnt)             s[i] = chose(s1[i], s2[i]);           else if (p % 2 == 1)             s[i] = s1[i];           else             s[i] = s2[i];         }       }     } else {       for (int i = 0; i < n; i++) {         if (s1[i] == s2[i]) {           q++;           if (q <= t - cnt)             s[i] = chose(s1[i], s1[i]);           else             s[i] = s1[i];         } else {           p++;           s[i] = chose(s1[i], s2[i]);         }       }     }     printf( %s , s);     return 0;   }   