N = int(input())

base = ["3", "5", "7"]
nums = ["3", "5", "7"]
temp = []
x = 0

while 1:
    for num in nums[(3**x)-1:]:
        for b in base:
            temp.append(b + num)
    nums.extend(temp)
    
    x += 1
    if int(temp[-1]) > 10**9:
        break
    temp = []

target = []
for n in set(nums):
    if "7" in n and "5" in n and "3" in n:
        target.append(int(n))

count = 0
target.sort()
for n in target:
    if int(n) < N:
        count += 1

print(count)