mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    N = int(input())
    S = input().rstrip('\n')

    ans = 0
    for i in range(N):
        for k in range(i+1, N):
            if i%2 == k%2:
                j = (i+k) // 2
                if S[i] == "U" and S[j] == "M" and S[k] == "G":
                    ans += 1
    print(ans)


if __name__ == '__main__':
    main()