#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int main()
{
    long long x,t,n;
    scanf("%lld%lld",&x,&t)
    
        if(x>=t)
    {
        n=x-t;
    printf("%lld\n",n);
    }
    else if(x<t)
    {
        printf("0\n");
    }
  
    return 0;
}

