macro_rules! read {
  ($x:ident, $v:expr, $idx:expr, $type:ty) => {
    let $x:$type = $v[$idx].clone().parse().unwrap();
  };

  ( $($x:ident:$t:ty),* ) => {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let input:Vec<String> = s.trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect();
    let mut idx:i64 = -1;
    $(
      idx += 1;
      read!($x, input, idx as usize, $t);
    )*
  };
}

fn main() {
  read!(n:usize);
  read!(s:String);

  let cs = s.chars().collect::<Vec<char>>();

  let ans = (0..cs.len()-2).fold(0, |acc1, ui| {
    if cs[ui] == 'U' {
      acc1 + (ui..cs.len()-1).fold(0, |acc2, mi| {
        if cs[mi] == 'M' && mi+mi-ui < cs.len() && cs[mi+mi-ui] == 'G' {
          acc2 + 1
        } else {
          acc2
        }
      })
    } else {
      acc1
    }
  });

  println!("{}", ans);
}