N = int(input())
S = input()
c1 = [0] * N
c2 = [0] * N
ans = N
for i in range(N):
    c1[i] += c1[i - 1] + 1 * (S[i] == "#")
    c2[i] += c2[i - 1] + 1 * (S[i] == ".")
c1 = [0] + c1
c2 = [0] + c2
for i in range(N):
    ans = min(ans, c1[i + 1] + c2[N] - c2[i + 1])
print(ans)