n=int(input())
s=input()
ans=0

for kankaku in range(len(s)):
    if 3 + 2*kankaku > len(s):
        break
    for i in range(len(s)):
        j=i+1+kankaku
        k=j+1+kankaku
        if k >= len(s):
            break
        if s[i] == 'U' and s[j] == 'M' and s[k] == 'G':
            ans+=1
            
print(ans)