N = int(input())
S = input()
candidates = ((i,j,k) for i in range(N - 2) for j in range(N - 1) for k in range(N) if i < j < k and j - i == k - j and S[i] == "U" and S[j] == "M" and S[k] == "G")
count = len(list(candidates))
print(count)