N = int(input())
S = input()

result = 0
i = 0
while True:
    i = S.find('U', i)
    if i == -1:
        break
    j = i + 1
    while True:
        j = S.format('M', j)
        if j == -1:
            break
        k = j + 1
        while True:
            k = S.format('G', k)
            if k == -1:
                break
            result += 1
print(result)