
function Main(input) {
    var a = parseInt(input[0], 10);
    var b = parseInt(input[1], 10);
    var c = parseInt(input[2], 10);

    var utusu = a - b;
    console.log((c - utusu) < 0 ? 0 : (c - utusu));
}

Main(require("fs").readFileSync("/dev/stdin", "utf8").trim().split(/\n|\s/));