N = int(input())
S = input()
cnt = 0
for i in range(N-1):
    for k in range(i+1,N):
        if (i + k)%2 == 0:
            j = (i+k)//2
            if S[i] == 'U' and S[j] == 'M' and S[k] == 'G':
                cnt += 1
print(cnt)