func_code_string: #include <bits/stdc++.h>   using namespace std;   int find(string s, string sub, int begin, int end) {     for (int i = begin; i < end - 1; i++)       if (s[i] == sub[0] && s[i + 1] == sub[1]) return i;     return -1;   }   int main() {     string s, sub;     cin >> s;     int size = s.size();     int index1, index2, index3, index4;     index1 = find(s,  AB , 0, size);     index2 = find(s,  BA , 0, size);     index3 = find(s,  BA , index1 + 2, size);     index4 = find(s,  AB , index2 + 2, size);     if ((index1 + 1 && index3 + 1) || (index2 + 1 && index4 + 1))       cout <<  YES ;     else       cout <<  NO ;     return 0;   }   