import sys
input = sys.stdin.readline

N = int(input())
S = input().rstrip()
ans = 0
x = 0
for i in range(N)[::-1]:
    if S[i] == '.':
        if i < N-1 and S[i+1] == '.':
            x = max(0, x - 1)
        continue
    if i < N-1 and S[i+1] == '#':
        x += 1
    ans = max(ans, N-i+x)
print(ans)