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.PrintWriter;
import java.util.Scanner;

public class A {
    static Scanner in; static int next() throws Exception {return in.nextInt();};
//	static StreamTokenizer in; static int next() throws Exception {in.nextToken(); return (int) in.nval;}
//	static BufferedReader in;
    static PrintWriter out;

    public static void main(String[] args) throws Exception {
        in = new Scanner(System.in);
//		in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
//		in = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);


        int n = next(), a = next(), b = next();

        out.println(Math.min(n-a,b+1));

        out.println();
        out.close();
    }
}