import java.util.Scanner;
public class No126 {
	public static void main (String[] args)
	{
		Scanner sc=new Scanner(System.in);
		int a,b,s,count;
		a=sc.nextInt();
		b=sc.nextInt();
		s=sc.nextInt();
		count=0;
		if(a==0){count++;a++;};
		if(a>s)count+=a;
		else count+=Math.min(Math.abs(a-s),Math.abs(b-s))+s;
		System.out.println(count);
	}
}