"use strict";

const input = require("fs").readFileSync("/dev/stdin", "utf8");

const inputs = input.split(" ");
const A = Number(inputs[0]);
const B = Number(inputs[1]);
const C = Number(inputs[2]);

const main = (A, B, C) => {
  let space = A - B;
  if (space >= C) {
    return 0;
  } else {
    return C - space;
  }
};

console.log(main(A, B, C));