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 l1 = Math.abs(S - A);
		int l2 = Math.abs(S - B);
		if(l1 <= l2) {
			int ans = l1 + S;
			System.out.println(ans);
		}else {
			int ans = l2;
			if(A == 0) {
				ans += 2 + S - 1;
				System.out.println(ans);
				System.exit(0);
			}
			int t1 = l1 + A;
			int t2 = S + Math.abs(A - 1);
			ans += Math.min(t1, t2);
			System.out.println(ans);
		}
	}
}