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.
/*Author LAVLESH*/
import java.util.*;
import java.io.*;
public class solution{
	static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	static StringTokenizer st=new StringTokenizer("");
    static public String next(){
	        while (st == null || !st.hasMoreTokens()) {
	            try {
	                st = new StringTokenizer(br.readLine());
	            } catch (IOException e) {
	                throw new RuntimeException(e);
	            }
	        }
	        return st.nextToken();
	    }
	
	
	public static void main(String[]args)throws IOException{
		PrintWriter op =new PrintWriter(System.out);
	     int n=Integer.parseInt(next());
	     int a=Integer.parseInt(next());
	     int b=Integer.parseInt(next());
	    int i=1;int ans=0;
	     while(i<=n){if(i>a&&i>=n-b&&i<=n){ans++;}i++;}
	    	op.print(ans);
	     op.close();
  }
}

