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