func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, k;     scanf( %d%d , &n, &k);     vector<char> s(n + 1), t(n + 1);     scanf( %s , &s[0]);     scanf( %s , &t[0]);     long long ans = 0;     long long cnt_a = 0;     long long cnt_b = 0;     bool found_diff = false;     bool big_num = false;     for (int i = 0; i < n; ++i) {       if (found_diff && !big_num) {         cnt_a = cnt_a * 2 + (s[i] ==  a  ? 1 : 0);         cnt_b = cnt_b * 2 + (t[i] ==  b  ? 1 : 0);       }       if (s[i] != t[i]) {         found_diff = true;       }       if (found_diff) {         ans += min(cnt_a + cnt_b + 2, (long long)k);         if (cnt_a + cnt_b + 2 >= k) {           big_num = true;         }       } else {         ++ans;       }     }     printf( %lld n , ans);     return 0;   }   