from itertools import product

N = int(input())
cnt = 0
num = [str(i) for i in range(10)]
for i in range(3, 16, 3):
    if len(str(N)) < i:
        break
    for v in product(num, repeat = i//3):
        if v[0] == '0':
            continue
        s = ''.join(v)
        s = 3 * s
        if int(s)<=N:
            cnt += 1
print(cnt)