n = int(input())
s = str(input())
ans = 0
for i in range(n-2):
    for k in range(i+2, n):
        if (i+k)%2 != 0:
            continue
        else:
            j = (i+k)//2
            if s[i] == 'U' and s[j] == 'M' and s[k] == 'G':
                ans += 1
print(ans)