object Main{

def main(args: Array[String]): Unit = {
  val arr1 = io.StdIn.readLine().split(' ')
  val a = arr1(0).toInt
  val b = arr1(1).toInt
  val c = arr1(2).toInt
  
  if (a - b >= c) println(0) else println(c - (a - b) )
}
}
