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.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class Main4 {
    
    static class Main {
        
        public Scanner sc;
        
        public void run() {
            int n = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
            System.out.println(Math.min(b+1, n-a));
        }
        
    }
    
    public static void main(String[] args) {
        Main main = new Main();
        try { main.sc = new Scanner(new FileInputStream("test.in")); }
        catch (FileNotFoundException e) { main.sc = new Scanner(System.in); }
        main.run();
    }
    
}