func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     string s;     cin >> s;     int ans = 0, flag = 1;     for (int i = 0; i < n; i++) {       if (s[i] !=  ? ) {         if (s[i] == s[i + 1]) {           flag = 0;         }       } else if (i == 0 || i == n - 1 || s[i + 1] == s[i - 1] || s[i + 1] ==  ? )         ans = 1;     }     if (flag && ans)       cout <<  YES  << endl;     else       cout <<  NO  << endl;   }   