N = int(input())
S = input()
 
# at position 0
l_b = 0
r_w = S.count('.')
 
needHand = 2 * 10**5
for i,v in enumerate(S):
  if S[i] == '#': #black
    l_b += 1
  else:
    r_w -= 1
  ret = l_b + r_w
  
  if ret <= needHand:
    needHand = ret
 
ans = needHand
print("{}".format(ans))