func_code_string: #include <bits/stdc++.h>   #pragma GCC optimize( O3 )   #pragma GCC optimize( unroll-loops )   #pragma GCC optimize( no-stack-protector )   #pragma GCC target( sse,sse2,ssse3,sse3,sse4,popcnt,avx,mmx,abm,tune=native )   using namespace std;   signed main() {     cin.tie(nullptr)->sync_with_stdio(false);     long long n, k;     cin >> n >> k;     string s, t;     cin >> s >> t;     long long ans = 0, hv = 1;     for (long long i = 0; i < n; i++) {       if (hv < k) {         hv *= 2;         if (s[i] == t[i]) {           hv--;         } else if (s[i] ==  b  && t[i] ==  a ) {           hv -= 2;         }         hv = min(hv, k);       }       ans += hv;     }     cout << ans <<   n ;   }   