Problem:
Score : 100 points

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.

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

Solution in PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php
  fscanf(STDIN, "%d", $amout);  
  $array = explode(' ', fgets(STDIN));

  $nums = array();
  for($i=0 ; $i < $amout; $i++){
    $value = (int)$array[$i];
    $nums[] = $value;
    $nums[] = $value - 1;
    $nums[] = $value + 1;
  }

$tmpArray = array_count_values($nums);
ksort($tmpArray);

echo max($tmpArray);