import sys

sys.setrecursionlimit(10 ** 6)
stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline().strip()
nsa = lambda: list(map(str, stdin.readline().split()))
ntp = lambda: tuple(map(int, stdin.readline().split()))
mod = 10 ** 9 + 7
inf = 10 ** 18

n = ni()
S = ns()
ans = 0
for i in range(n):
    for j in range(i + 1, n):
        k = 2 * (j + 1) - (i + 1) - 1
        if j < k < n:
            if S[i] == 'U' and S[j] == 'M' and S[k] == 'G':
                ans += 1

print(ans)