func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<int> mil, omil;   int main() {     int n, t;     string a, b;     char c[100010];     cin >> n >> t;     cin >> a;     cin >> b;     t = n - t;     for (int i = 0; i < a.size(); i++) {       if (a[i] == b[i])         mil.push_back(i);       else         omil.push_back(i);     }     if (mil.size() < t) {       t -= mil.size();       if (omil.size() < (2 * t)) {         puts( -1 );         return 0;       }       for (int i = 0; i < mil.size(); i++) c[mil[i]] = a[mil[i]];       for (int i = 0; i < t; i++) c[omil[i]] = a[omil[i]];       for (int i = t; i < 2 * t; i++) c[omil[i]] = b[omil[i]];       for (int i = 2 * t; i < omil.size(); i++) {         for (char ch =  a ; ch <=  z ; ch++) {           if (ch != a[omil[i]] && ch != b[omil[i]]) {             c[omil[i]] = ch;             break;           }         }       }       puts(c);       return 0;     }     for (int i = 0; i < t; i++) c[mil[i]] = a[mil[i]];     for (int i = t; i < mil.size(); i++) {       for (char ch =  a ; ch <=  z ; ch++) {         if (ch != a[mil[i]] && ch != b[mil[i]]) {           c[mil[i]] = ch;           break;         }       }     }     for (int i = 0; i < omil.size(); i++) {       for (char ch =  a ; ch <=  z ; ch++) {         if (ch != a[omil[i]] && ch != b[omil[i]]) {           c[omil[i]] = ch;           break;         }       }     }     puts(c);   }   