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

result = 0
i = -1
while i < N:
    i = S.find('U', i + 1)
    if i == -1:
        break
    j = i
    while j < N:
        j = S.find('M', j + 1)
        if j == -1:
            break
        k = j
        while k < N:
            k = S.find('G', k + 1)
            if k == -1:
                break
            if j - i != k - j:
                continue
            result += 1
            #print(i, j, k)
print(result)