import java.util.Scanner

object Main {
  def main(args: Array[String]): Unit = {
    //nextLineとnextを同時に使ったら死ぬ
    val sc = new Scanner(System.in)
    val x, t = sc.nextLong()
    println(math.max(x - t, 0))
  }

  def debug(args: Any*): Unit = {
    Console.err.println(args.mkString(" "))
  }
}
