N = int(eval(input()))

S = eval(input())



count_if_all_white = 0

for c in S:

    if c == "#":

        count_if_all_white += 1



l_count = 0

r_count = sum([1 for c in S if c == "."])

count_if_contain_black = l_count+r_count

for c in S:

    if c == "#":

        l_count += 1

    else:

        r_count -= 1

        

    count_if_contain_black = min(count_if_contain_black, l_count+r_count)



print((min(count_if_all_white, count_if_contain_black)))
N = int(eval(input()))

S = eval(input())



l_count = 0

r_count = sum([1 for c in S if c == "."])

count_if_contain_black = l_count+r_count

count_if_all_white = 0

for c in S:

    if c == "#":

        l_count += 1

        count_if_all_white += 1

    else:

        r_count -= 1

        

    count_if_contain_black = min(count_if_contain_black, l_count+r_count)



print((min(count_if_all_white, count_if_contain_black)))
N = int(eval(input()))
S = eval(input())
count_if_all_white = 0
for c in S:
    if c == "#":
        count_if_all_white += 1
l_count = 0
r_count = sum([1 for c in S if c == "."])
count_if_contain_black = l_count + r_count
for c in S:
    if c == "#":
        l_count += 1
    else:
        r_count -= 1
    count_if_contain_black = min(count_if_contain_black, l_count + r_count)
print((min(count_if_all_white, count_if_contain_black)))

N = int(eval(input()))
S = eval(input())
l_count = 0
r_count = sum([1 for c in S if c == "."])
count_if_contain_black = l_count + r_count
count_if_all_white = 0
for c in S:
    if c == "#":
        l_count += 1
        count_if_all_white += 1
    else:
        r_count -= 1
    count_if_contain_black = min(count_if_contain_black, l_count + r_count)
print((min(count_if_all_white, count_if_contain_black)))

+l_count = 0 +r_count = sum([1 for c in S if c == "."]) +count_if_contain_black = l_count + r_count +        l_count += 1 -l_count = 0 -r_count = sum([1 for c in S if c == "."]) -count_if_contain_black = l_count + r_count -for c in S: -    if c == "#": -        l_count += 1