import sys
from itertools import accumulate
N = int(input())
S = input()
if S == '.'*N or S == '#'*N:
    print(0)
else:
    ind1 = 0
    for i, x in enumerate(S):
        if x == '#':
            ind1 = i
            break
        if i == N-1:
            print(0)
            sys.exit()
    num = 0
    for i, x in enumerate(S[::-1]):
        if x == '.':
            num = i
            break
        if i == N-1:
            print(0)
            sys.exit()
    ind2 = N - num
    if ind1 > ind2:
        print(0)
        sys.exit()
    s = S[ind1:ind2]
    if s[0] == '.' or s[-1] == '#' or len(s) == 0:
        print(0)
        sys.exit()
    else:
        a = s.split('.')
        b = s.split('#')
        aa = []
        bb = []
        for x, y in zip(a, b):
            if len(x) != 0:
                aa.append(len(x))
            if len(y) != 0:
                bb.append(len(y))
        d = [0] + list(accumulate(aa))
        e = [0] + list(accumulate(bb))
        p = d[-1]
        ls = []
        for i in range(len(d)):
            ls.append(e[i]+p-d[i])
        print(min(ls))