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.util.*;

public class Kross {
    public void solve() {
        int n =nextInt();
        int a =nextInt();
        int b =nextInt();
        if (n-a>b)
        System.out.print(b+1);
        else 
        System.out.print(n-a);
    }
public static void main (String[]args){
        new Kross().run();
    }

    BufferedReader br;
    StringTokenizer st;
    PrintWriter out;

    private void run () {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            //br = new BufferedReader(new FileReader("birthday.in"));
            //out = new PrintWriter(new FileWriter("birthday.out"));
            solve();
            br.close();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private int nextInt () {
        return Integer.parseInt(next());
    }

    private String next () {
        while (st == null || !st.hasMoreTokens()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
                return "END_OF_FILE";
            }
        }
        return st.nextToken();
    }
}