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

def dot_num ():
    cnt = 0
    for i in range (N):
        if S [i] == '.':
            cnt += 1
    return cnt

def hash_num ():
    cnt = 0
    for i in range (N):
        if S [i] == '#':
            cnt += 1
    return cnt

dots = dot_num ()
hashes = hash_num ()

if S [0] == '.' and S [1] == '#':
    dots -= 1

if S [N-1] == '#' and S [N-2] == '.':
    hashes -= 1
    
print (min (dots, hashes))
