import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int S = sc.nextInt();
        int min=0;
        int Amove=Math.abs(A-S);
        int Bmove=Math.abs(B-S);
        if(S==1){
            min=Amove+1;
        }else{
            if(Amove<=Bmove){
                min=Amove+S;
            }else{
                if(A>B||A==0){
                    min=Bmove+S+Math.abs(A-1);
                }else{
                    min=Bmove+S;
                }
            }
        }
        System.out.println(min);
    }
}