N = int(input())
S = input()
ans = 0
for x in range(1, N):
    for y in range(N):
        i = y
        j = i+x
        k = j+x
        #print(i, j, k)
        if k>=N:
            break
        if S[i]=='U' and S[j]=='M' and S[k]=='G':
            ans += 1
print(ans)