while 1:
    try:
        n = int(input())
        num_set = set()
        for i in range(7,n+1,7):
            num_set.add(i)
        for j in range(1,n+1):
            if "7" in str(j):
                num_set.add(j)
        print(len(num_set))
    except:
        break