import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int A = scan.nextInt();
		int B = scan.nextInt();
		int S = scan.nextInt();
		scan.close();
		int t1, t2;
		if(A == 0) {
			t1 = S + S;
			if(S - B > 0) {
				t2 = S - B + S + 1;
			}else {
				t2 = B - S + S + 1;
			}
			System.out.println(Math.min(t1, t2));
			System.exit(0);
		}
		if(S - A > 0) {
			t1 = S - A + S ;
		}else {
			t1 = A - S + S ;
		}
		if(S - B > 0) {
			t2 = S - B;
			if(S - A > 0) {
				t2 += S - A + A;
			}else {
				t2 += A - S + A ;
			}
		}else {
			t2 = B - S;
			if(S - A > 0) {
				t2 += S - A + A;
			}else {
				t2 += A - S + A ;
			}
		}
		int ans = Math.min(t1, t2);
		System.out.println(ans);
	}
}