function main(input) {
    var args = input.trim().split(" ");
    var A = Number(args[0]);
    var B = Number(args[1]);
    var C = Number(args[2]);

    var rest = A - (B + C);
    if (rest > 0) {
        console.log(0);
        return;
    }
    console.log(Math.abs(rest));
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));

