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

W = [0] * N
W[-1] += S[-1] == "."
for i in range(N - 2, -1, -1):
    W[i] = W[i + 1] + (S[i] == ".")

B = [0] * N
B[0] += S[0] == "#"
for i in range(1, N):
    B[i] = B[i - 1] + (S[i] == "#")

T = [w + b for w, b in zip(W, B)]
T = min(T)
print(min(T, W[0], B[-1]))
