func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string a, b;     cin >> a;     cin >> b;     int lena = a.length(), lenb = b.length();     if (lena != lenb)       cout <<  NO ;     else {       int count = 0;       char old1, old2;       for (int i = 0; i < lena && count < 3; i++) {         if (a[i] != b[i]) {           count++;           if (count == 1) {             old1 = b[i];             old2 = a[i];           }           if (count == 2 && (a[i] != old1 || b[i] != old2)) count = 3;         }       }       if (count == 2)         cout <<  YES ;       else         cout <<  NO ;     }     return 0;   }   