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 C (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
	int i, j, imax, jmax = 0, count = 0;
	int *buf = calloc(1, 100001 * sizeof(int));
	
	scanf("%d", &imax);
	
	for (i = 0; i < imax; i++) {
		int tmp;
		scanf("%d", &tmp);
		if (jmax < tmp) {
			jmax = tmp;
		}
		if (tmp == 0) {
			buf[tmp] = buf[tmp] + 1;
			buf[tmp + 1] = buf[tmp + 1] + 1;
		} else {
			buf[tmp - 1] = buf[tmp - 1] + 1;
			buf[tmp] = buf[tmp] + 1;
			buf[tmp + 1] = buf[tmp + 1] + 1;
		}
	}
	
	for (j = 0; j < 100000; j++) {
		if (count <= buf[j]) {
			count = buf[j];
		}
	}
	
	printf("%d", count);
	return 0;
}