Petr stands in line of n people, but he doesn't know exactly which position he occupies. He can say that there are no less than a people standing in front of him and no more than b people standing behind him. Find the number of different positions Petr can occupy.

Input

The only line contains three integers n, a and b (0 ≤ a, b < n ≤ 100).

Output

Print the single number — the number of the sought positions.

Examples

Input

3 1 1


Output

2


Input

5 2 3


Output

3

Note

The possible positions in the first sample are: 2 and 3 (if we number the positions starting with 1).

In the second sample they are 3, 4 and 5.
import java.io.*;
import java.util.*;
  
public class Main {
	public static void main(String[] args) throws Exception {
		PrintWriter pr = new PrintWriter(System.out,true);
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer tz = new StringTokenizer(in.readLine());   
		//Scanner s = new Scanner(System.in);
		int n = Integer.parseInt(tz.nextToken());
		int a = Integer.parseInt(tz.nextToken());
		int b = Integer.parseInt(tz.nextToken());
		int res = 0;
		for(int i = 0;i < n;i++) {
			if(i >= a && (n-1-i) <= b) res++;
		}
		pr.println(res);
	}
}