Score : 400 points
A positive integer X is said to be a lunlun number if and only if the following condition is satisfied:
For example, 1234, 1, and 334 are lunlun numbers, while none of 31415, 119, or 13579 is.
You are given a positive integer K. Find the K-th smallest lunlun number.
Input is given from Standard Input in the following format:
K
Print the answer.
15
23
We will list the 15 smallest lunlun numbers in ascending order:
1,
2,
3,
4,
5,
6,
7,
8,
9,
10,
11,
12,
21,
22,
23.
Thus, the answer is 23.
1
1
13
21
100000
3234566667
Note that the answer may not fit into the 32-bit signed integer type.