n = int(input())
s = str(input())
b = []
nb = 0
w = []
nw = 0
for s_ in s:
  if s_ == "#":
    nb += 1
  if s_ == ".":
    nw += 1
  b.append(nb)
  w.append(nw)
ans = []
for i in range(n):
  ans.append(b[i]+w[n-1]-w[i])
print(min(ans))
