fn main() {
    let mut n: String = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut s: String = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let s: Vec<char> = s.trim().chars().collect();

    let mut result = 0;
    for i in 1..n {
        if 2*i >= n { break; }
        for start in 0..n {
            if start + 2*i >= n { break; }
            if s[start] == 'U' && s[start+i] == 'M' && s[start+2*i] == 'G' {
                result += 1;
            }
        }
    }
    println!("{}", result);
}