function main(input) {
  const temp = input.trim().split(' ');
  const x = parseInt(temp[0], 10);
  const t = parseInt(temp[1], 10);
  const a = x - t;
  if (a >= 0) {
    console.log(a);
  } else {
    console.log(0);
  }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));