import std.stdio, std.conv, std.string, std.array, std.range, std.algorithm, std.container;
import std.math, std.random, std.bigint, std.datetime, std.format;
void main(string[] args){ if(args.length > 1) if(args[1] == "-debug") DEBUG = 1; solve(); }
void log()(){ writeln(""); } void log(T, A ...)(T t, lazy A a){ if(DEBUG) write(t, " "), log(a); } bool DEBUG = 0; 
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }
T read(T)(){ return read.to!T; }
T[] read(T)(long n){ return n.iota.map!(_ => read!T).array; }
T[][] read(T)(long m, long n){ return m.iota.map!(_ => read!T(n)).array; }
// ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- //

/*
If you find s_i > s_(i + 1), swap them.
Othewise, NO.
*/

void solve(){
	int n = read!int;
	string s = readln.chomp;
	
	int i1;
	bool f = 0;
	foreach(i; 0 .. n - 1){
		if(s[i] > s[i + 1]){
			i1 = i;
			f = 1;
			break;
		}
	}
	if(f == 0) writeln("NO");
	else writeln("YES"), writeln(i1 + 1, " ", i1 + 2);
}
