from bisect import bisect

N = int(input())
X = list(range(12, 100, 3))
for i in range(16, 4 ** 9 + 1):
    x = i
    tmp = 0
    j = 0
    while x > 0:
        tmp += (x % 4) * 3 * (10 ** j)
        x //= 4
        j += 1
    if tmp < 100:
        continue
    if tmp > N:
        break
    X.append(tmp)
print(bisect(X, N))