n=input()
n_int = int(n)

if n_int<357:
  print(0)
else:
  counter__ = 0
  for k in range(3 ,len(n)+1):
    counter__ += recursive_f([])

    def recursive_f(A):
      if len(A) == k:     # Aはリスト[7,7,7]
        A_ = int("".join(map(str,A)))    # A_はint 777
        counter = 0
        # print(A_)
        if len(set(A)) == 3 and A_ <= n_int:
          counter += 1
          return counter

        counter_ = 0

        for i in [3,5,7]:
          A.append(i)
          counter_ += recursive_f(A)
          A.pop()

          return counter_
        
print(counter__)