package no126;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = sc.nextInt();
		System.out.println(solve(a,b,c));
	}

	public static int solve(int a,int b,int s) {
		int la = Math.abs(a-s);
		int lb = Math.abs(b-s);
		int ans = 0;
		if (a == 0) {
			if (la <= lb) {
				return la + s;
			}else{
				return lb + s + 1;
			}
		}else{
			if (la <= lb) {
				return la + s;
			}else{
				return  Math.min(lb + Math.abs(a-b) + a,lb + (s-1) + a);
			}
		}
	}

}