#include <bits/stdc++.h>
using namespace std;
#define int              long long int
#define double           long double
#define print(a)         for(auto x : a) cout << x << " "; cout << endl


const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;

inline int power(int a, int b, int mod=M) {
    int x = 1;
    a %= mod;
    while (b) {
        if (b & 1) x = (x * a) % mod; 
        a = (a * a) % mod;
        b >>= 1;
    }
    return x;
}


//_ ***************************** START Below *******************************




string a;

void consistency(int n){

    int i = 1;
    while(i<n && a[i] >= a[i-1]) i++;
    if(i==n){
        cout << "NO" << endl;
        return;
    }
    
    cout << "YES" << endl;
    
    //* a-z -> index 
	vector<int> mp(26, -1);
	for(int i=0; i<n; i++){
		int k = a[i]-'a';
		mp[k] = i;
		
		for(int j=k+1; j<26; j++){
			if(mp[j] != -1 ){
				cout << mp[j]+1 << " " << i+1 << endl;
				return;
			}
		}
	}
    
}








void solve() {
    
    int n;
    cin>> n;
    
    cin >> a;
    consistency(n);


}





int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }

    return 0;
}