function main(input) {
  input=input.trim();
  const x = parseInt(input.split(" ")[0], 10);
  const t = parseInt(input.split(" ")[1], 10);
  if(t>=x){
    console.log(0);
  }else{
    console.log(x-t);
  }
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));