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

}