N = int(input())
if N < 100:
    print((N-9)//3)
    exit()
ans = 15
N2 = []
while N > 0:
    N2.append(N % 10)
    N //= 10
LN = len(N2)
tmp = 0
j = LN
for i in reversed(N2):
    if i % 3 == 0:
        tmp += i//3 * (4 ** (j-1))
    else:
        tmp += i//3 * (4 ** (j-1))
        tmp += 4 ** (j-1)
        tmp -= 1
        break
    j -= 1
print(ans + tmp)