问题描述：
给定一个0到9999之间的整数，请以四个字符的形式打印该数字，如果数字不足四位数，则在前面补0.
例如，输入：548
则输出 0548
又如，输入3786
则输出 3786
Problem Statement
You are given an integer NN between 00 and 99999999 (inclusive).
Print it as a four-digit string after appending to it the necessary number of leading zeros.
Constraints
-
0 \leq N \leq 99990≤N≤9999
-
NN is an integer.
Input
Input is given from Standard Input in the following format:
NN