N = int(input())
S = input()

A = [0] * N
i = 0
while S[i] == ".":
    i += 1
S = S[i:]
N = len(S)

for i, s in enumerate(S):
    if s == "#":
        A[i] = A[i - 1] + 1
    else:
        A[i] = A[i - 1] - 1

x = S.index("#")
y = max(A)
print(N - x + y - 1)