object Main { 
  def main(args:Array[String]) {
    val ABC = readLine().split(' ').map(_.toInt).toList
    val A = ABC(0)
    val B = ABC(1)
    val C = ABC(2)

    var ans = 0
    if(A - B >= C) ans = 0
    else ans = C - (A - B)
    println(ans)
  }
}
