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