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题库练习 [COCI-2010_2011-contest1]#3 SRETAN
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A1189 | [COCI-2010_2011-contest1]#3 SRETAN

来源COCI
时间限制1s
内存限制128MB
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题目描述

Digits 4 and 7 are lucky, while all others are unlucky. An integer is lucky if it contains only lucky digits in decimal notation. We would like to know the K-th lucky positive integer.

输入格式

The first and only line of input contains a positive integer K (1 ≤ K ≤ 10^9).

输出格式

The first and only line of output must contain the K-th lucky positive integer.

输入输出样例

输入 #1
1
输出 #1
4
输入 #2
2
输出 #2
7
输入 #3
3
输出 #3
44
C++ 编辑器
输入
输出