from collections import defaultdict
from sys import stdin

def main():
    N = int(input())
    S = input()

    txt = defaultdict(list)
    for i, s in enumerate(S, start=1):
        txt[s].append(i)

    ans = 0
    for j in txt['M']:
        for i in txt['U']:
            k = j - i + j
            if k in txt['G']:
                ans += 1
    print(ans)

input = lambda: stdin.readline().rstrip()
main()