N=int(input())
S=input()
res=0
for le in range(1,N//2+1):
    for st in range(N-le*2):
        #print(st,le,S[st],S[st+le],S[st+le*2])
        if S[st]=='U' and S[st+le]=='M' and S[st+le*2]=='G':
            res+=1
print(res)