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?

Constraints

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

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.