use std::io::Read;

fn main() {
	let mut s = String::new();
	std::io::stdin().read_to_string(&mut s).ok();
	let mut l = s.lines();
	let n: usize = l.next().unwrap().parse().unwrap();
	let c: Vec<_> = l.last().unwrap().chars().collect();
	let mut a = 0;
	for i in 0..n {
		if c[i] == 'U' {
			for j in 1..n {
				if i + j + j < n && c[i + j] == 'M' && c[i + j + j] == 'G' {
					a += 1;
				}
			}
		}
	}
	println!("{}", a)
}