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.lang.*;
import java.math.*;
import java.util.*;
import java.util.regex.*;
public final class Solution{
	public static void main(String[] args)throws Exception{//pg 34 <--- upto 32...
		new Solution().solve();
	}
	public static void solve()throws Exception{
		String[] s;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		s = br.readLine().split(" ");
		br.close();
		int n = Integer.parseInt(s[0]);
		int a = Integer.parseInt(s[1]);
		int b = Integer.parseInt(s[2]);
		int count = 0;
		for(int i=a+1;i<=n;i++){
			if(i-1>=a && n-i<=b){
				count++;
			}
		}
		System.out.println(count);
	}
}