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.*;
import java.lang.*;

public class Main{
	
	public static void main(String[] args) throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String s = br.readLine();
		String[] temp = s.split(" ");

		int n=Integer.parseInt(temp[0]);
		int a=Integer.parseInt(temp[1]);
		int b = Integer.parseInt(temp[2]);
		int count=0;
		
		for(int i=1;i<=n;i++){
			if(i>a && n-i<=b) count++;
		}
		
		System.out.println(count);
		
	}
}
		
		