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