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.*;
public class cf_Party
 {
     static int mod=1000000007;
    public static void main (String[] args)  throws IOException 
     {
         BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
        int t=1; 
        while (t-- > 0) 
        { 
        	StringTokenizer tok=new StringTokenizer(br.readLine()," ");
            int n=Integer.parseInt(tok.nextToken());
            int a=Integer.parseInt(tok.nextToken());
            int b=Integer.parseInt(tok.nextToken());
            int count=0;
            for(int i=1;i<=n;i++) {
            	if(i-1>=a && n-i<=b) {
            		count++;
            	}
            
            }
            System.out.println(count);
        }
        
        
    }
    
}