Problem F: 教学楼比大树高多少米?

Problem F: 教学楼比大树高多少米?

[Creator : ]
Time Limit : 1.000 sec  Memory Limit : 128 MiB

Description

教学楼高a米,旁边的大树高b米,教学楼比大树高多少米?

Sample Input Copy

12 8

Sample Output Copy

4