package main

import "fmt"

func main() {
	var N, ans int
	var S string
	fmt.Scan(&N)
	fmt.Scan(&S)
	for d := 1; 2*d < N; d++ {
		for i := 0; i+2*d < N; i++ {
			if S[i] == 'U' && S[i+d] == 'M' && S[i+2*d] == 'G' {
				ans++
			}
		}
	}
	fmt.Println(ans)
}