#include <bits/stdc++.h>
using namespace std;
const long long LLMAX = 2e18;
const int MOD = 1e9 + 7;
const double eps = 1e-8;
const int MAXN = 1e6 + 10;
inline long long sqr(long long x) { return x * x; }
inline int sqr(int x) { return x * x; }
inline double sqr(double x) { return x * x; }
long long __gcd(long long a, long long b) {
  return b == 0 ? a : __gcd(b, a % b);
}
long long qpow(long long a, long long n) {
  long long sum = 1;
  while (n) {
    if (n & 1) sum = sum * a % MOD;
    a = a * a % MOD;
    n >>= 1;
  }
  return sum;
}
inline int dcmp(double x) {
  if (fabs(x) < eps) return 0;
  return (x > 0 ? 1 : -1);
}
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  string s;
  cin >> n >> s;
  for (int i = 1; i < n; i++) {
    if (s[0] > s[i]) {
      cout << "YES" << endl;
      cout << 1 << ' ' << i + 1 << endl;
      return 0;
    }
  }
  cout << "NO" << endl;
  return 0;
}
