PROGRAMMING:Set subtraction
Given two nonempty sets a and B, the elements of the set are positive integers within 30000, write a program to find a-b.
###Input format:
The input is three lines. The first line is two integers n and m, which are the number of elements contained in the set a and B respectively, 1 ≤ n, m ≤ 10000. The second line represents the set a, which is a positive integer with n spaces, and each positive integer does not exceed 30000. The third line represents the set B, which is a positive integer with m spaces, and each positive integer does not exceed 30000.
###Output format:
The output is a line of integers, representing a-b. each integer is followed by a space, and each element is output in increasing order. If A-B is an empty set, output 0, and there is no space after 0.
###Input example:
```in
5 5
1 2 3 4 5
3 4 5 6 7
```
###Output example:
```out
1 2
```
answer：If there is no answer, please comment
###Input format:
The input is three lines. The first line is two integers n and m, which are the number of elements contained in the set a and B respectively, 1 ≤ n, m ≤ 10000. The second line represents the set a, which is a positive integer with n spaces, and each positive integer does not exceed 30000. The third line represents the set B, which is a positive integer with m spaces, and each positive integer does not exceed 30000.
###Output format:
The output is a line of integers, representing a-b. each integer is followed by a space, and each element is output in increasing order. If A-B is an empty set, output 0, and there is no space after 0.
###Input example:
```in
5 5
1 2 3 4 5
3 4 5 6 7
```
###Output example:
```out
1 2
```
answer：If there is no answer, please comment