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

ans = 0
for j, x in enumerate(S):
    if j != 0 and j != N-1 and x == 'M':
        for l in range(1, min(j+1, N-j)):
            if S[j-l] == 'U' and S[j+l] == 'G':
                ans += 1
print(ans)