One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.
n = int(input())
temp = n
dp = []
digitCount = 0
while (temp != 0):
    dp.append(temp % 10)
    temp = int(temp/10)
    digitCount += 1
dp.reverse()
sum = 0
for i in range(digitCount - 1):
    sum += 2**i
two = 2**(digitCount-1)
if(dp[0]==1):
    for i in range(1,len(dp)):
        if(dp[i]>1):
            break
        elif(dp[i]==1):
            continue
        else:
            two-=2**(digitCount-i-1)
sum+=two
print(sum)