시간 제한 메모리 제한 제출 정답 맞은 사람 정답 비율
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## 문제

창영이는 4와 7로 이루어진 수를 좋아한다. 창영이가 좋아하는 수 중에 K번째 작은 수를 구해 출력하는 프로그램을 작성하시오.

## 입력

첫째 줄에 K(1<=K<=109)가 주어진다.

## 출력

첫째 줄에 창영이가 좋아하는 숫자 중 K번째 작은 수를 출력한다.

## 예제 입력 1

1


## 예제 출력 1

4


## 예제 입력 2

2


## 예제 출력 2

7


## 예제 입력 3

3


## 예제 출력 3

44

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