n = int(input())
s = '.'+input()
lb, rw = 0, s.count('.')-1
ans = lb+rw
for i in range(1,n+1):
  if s[i] == '#':
    lb += 1
  elif s[i] == '.':
    rw -= 1
  if lb+rw < ans:
    ans = lb+rw
print(ans)