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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class TheNumberOfPosition {
    public static void main(String[] args) throws IOException{
        BufferedReader rd = new BufferedReader(new InputStreamReader(System.in));
        String line = rd.readLine();
        StringTokenizer tk = new StringTokenizer(line);
        ArrayList<Integer> arr = new ArrayList<Integer>();
        int n = Integer.parseInt(tk.nextToken());
        int f = Integer.parseInt(tk.nextToken());
        int b =Integer.parseInt(tk.nextToken());
        int sxvaoba = n-f;
        if(sxvaoba - b - 1 <0){
            System.out.println(sxvaoba);
            return;
        }else {
            System.out.println(b+1);
        }
        
        
    }
}
