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.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
public class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt(),m=sc.nextInt(),k=sc.nextInt();//String p = sc.next();
		int ans=0;
		int a=0;
		for(int i=1;i<=n;i++){
		    //System.out.println(a+" "+(n-i));
		    if(a>=m && n-i<=k){
		        ans++;
		    }
		    a++;
		}
		System.out.println(ans);
	}
	private static boolean isPrime(int n){
		
		for(int i=2;i<=Math.sqrt(n);i++){
			if(n%i==0 || n%5!=1){
				return false;
			}
		}
		return true;
	}
}
