function Main(input){
var A = new Number(input.split(" ")[0]);
var B = new Number(input.split(" ")[1]);
var C = new Number(input.split(" ")[2]);
var unA = A - B;
var remC = C -unA;
if(remC <= 0){
  console.log(0);
}else{
  console.log(remC);
}
}
  Main(require('fs').readFileSync('/dev/stdin','utf8'));