N =int(input())
S =[i for i in input()]
dic = {"U":[],"M":[],"G":[]}
for i,str in enumerate(S):
    dic[str].append(i)
ans = 0
for i in dic["U"]:
    for j in dic["G"]:
        if (i+j)%2==0 and (i+j)//2 in dic["M"]:
            ans += 1
print(ans)