package com.company;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        float M;
        float S;
        float A;
        float Raz = 0;
        float Raz2 = 0;
        float Raz3 = 0;
        Scanner in =new Scanner(System.in);

        M = in.nextFloat();
        S = in.nextFloat();
        A = in.nextFloat();
        Raz = M - S;
        Raz2 = S-A;
        Raz3 = Raz -Raz2;


        System.out.println(Raz3);

    }

}