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

cnt = 0
for i in S:
    if i == '#':
        cnt += 1
    else:
        break

ANS1 = S[cnt:].count('.') 

cnt = 0
newS = ''.join(list(reversed(S)))
for i in newS:
    if i == '#':
        cnt += 1
    else:
        break

ANS2 = newS[cnt:].count('.') 

print(min(ANS1, ANS2))