#include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     string s;     cin >> s;     for (int k = 0; k < n - 1; k++) {       if (s[k] > s[k + 1]) {         cout <<  YES  << endl;         cout << k + 1 <<     << k + 2;         return 0;       }     }     cout <<  NO ;     return 0;   }   