import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		int y = sc.nextInt();
		int d = sc.nextInt();
		int start = Math.max(0, d - x);
		int end = Math.min(y, d);
		System.out.println(Math.max(end - start + 1, 0));
	}
}