Problem description.
 
          JNTU College is conducting an Warmup contest for students to bring out their approaches of solving a problem. A Challenged B that he could not solve the problem.So help B in solving the problem.
     Given a series of numbers with only 3 and 4.Your task is very simple i.e.. find the nth number in the series. First few numbers in the number system are: 3, 4, 33, 34, 43, 44, 333, 334, 343, 344, 433, 434, 443, 444, 3333, 3334, 3343, 3344……..


Input
Input contains only a single integer N.

Output
Print the Nth number in the series

Constraints
Should contain all the constraints on the input data that you may have. Format it like:

1 ≤ N ≤ 100

 

Example
Input:
5

Output:
43
 

Explanation
If N=5 then the 5th number in the series will be 43.
Hence you need to print the output as 43 ...
read = lambda: map(int, raw_input().split())
read_s = lambda: map(str, raw_input().split())

def dfs(x, nums):
    if x > 1e10: return
    nums.append(x)
    dfs(x * 10 + 4, nums)
    dfs(x * 10 + 3, nums)

nums = []
dfs(0, nums)
nums.sort()
n, = read()
print nums[n]