import java.util.Scanner;

public class No_126 {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int s = sc.nextInt();
		int move = 0;
		sc.close();

		int dis_a = 0;
		int dis_b = 0;
		dis_a = Math.abs(a - s);
		dis_b = Math.abs(b - s);

		if (s == 1 || dis_b >= dis_a) {
			move += dis_a + s;
		} else if (a == 0) {
			move += dis_b + s + 1;
		} else {
			move += Math.min(dis_b+s+a-1, dis_b+a+dis_a);
		}
		System.out.println(move);
	}

}