def Run_Length_Encoding(S):
    """ランレングス圧縮

    S:文字列
    """
    if not S:
        return []

    R=[[S[0],1]]

    for i in range(1,len(S)):
        if R[-1][0]==S[i]:
            R[-1][1]+=1
        else:
            R.append([S[i],1])

    return R
#==================================================
N=int(input())
S=list(input())

a=0
for i in range(N):
    if S[i]=="#":
        a=i
        break

b=0
R=Run_Length_Encoding(S)
for s,r in R:
    if s=="#":
        b=max(b,r)

print((N-a)+b-1)