N = int(input())
S = str(input())
# '.'の場合は白, '#'の場合は黒

if S[0] == '.':
    count_white = [1]
    count_black = [0]
else:
    count_white = [0]
    count_black = [1]


for i in range(1, N):
    if S[i] == '.':
        # 見ている石が白なら
        count_white.append(count_white[i-1]+1)
        count_black.append(count_black[i-1])
    else:
        # 見ている石が黒なら
        count_white.append(count_white[i-1])
        count_black.append(count_black[i-1]+1)

tmp = 0
for i in range(N):
    min_sum = 0
    min_sum += count_black[i]
    min_sum += (count_white[N-1] - count_white[i])
    tmp = min(tmp, min_sum)

print(tmp)
