#include <bits/stdc++.h>   using namespace std;   int n;   string s;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     cin >> n >> s;     s =  ?  + s +  ? ;     int c = 0;     bool flag = true;     for (int i = 1; i <= n; i++) {       if (s[i] ==  ? ) {         c++;         if (s[i - 1] == s[i + 1] || s[i - 1] ==  ?  || s[i + 1] ==  ? ) {           flag = false;         }       }       if (s[i] == s[i - 1] && s[i] !=  ? ) {         flag = true;         break;       }     }     cout << (c == 0 || flag ?  NO  :  YES ) <<   n ;     return 0;   }   