Problem

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Problem: Find The K-th Lucky Number

Statement

A number is called lucky if it comprises only the digits $4$ and $7$ . Your task is to return the k-th lucky number as a string for a given integer k.

Constraints:

$1 <=$ k $<= 10^9$

Examples

Problem

Submissions

Problem: Find The K-th Lucky Number

Statement

A number is called lucky if it comprises only the digits $4$ and $7$ . Your task is to return the k-th lucky number as a string for a given integer k.

Constraints:

$1 <=$ k $<= 10^9$

Examples