Problem Statement

We have a sandglass that runs for X seconds. The sand drops from the upper bulb at a rate of 1 gram per second. That is, the upper bulb initially contains X grams of sand.
How many grams of sand will the upper bulb contains after t seconds?

Input

The input is given from Standard Input in the following format:
X t

Output

Print the number of sand in the upper bulb after t second.

Constraints

• 1≤X≤10^9
• 1≤t≤10^9
• X and t are integers.

Sample Input 1

100 17

Sample Output 1

83

17 out of the initial 100 grams of sand will be consumed, resulting in 83 grams.

Sample Input 2

48 58

Sample Output 2

0

All 48 grams of sand will be gone, resulting in 0 grams.

Sample Input 3

1000000000 1000000000

Sample Output 3

0

见题面 Input 部分

见题面 Output 部分