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.
/**
 * Created by Dima on 28.07.2014.
 */

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class CountOfPosition {
    private static BufferedReader reader;
    private static PrintWriter writer;
    private static StringTokenizer st;

    public static void main(String[] args) throws IOException {
        reader = new BufferedReader(new InputStreamReader(System.in));
        writer = new PrintWriter(System.out, true);
        solve();
    }

    private static void solve() throws IOException {
        int n = nextInt();
        int a = nextInt();
        int b = nextInt();
        int count = 0;
        for(int i = 0; i <= b; ++i) {
            if(n-i > a) ++count;
            else break;;
        }
        writer.println(count);
    }

    private static int nextInt() throws IOException {
        return Integer.parseInt(readToken());
    }

    private static String readToken() throws IOException {
        while (st == null || !st.hasMoreElements()) st = new StringTokenizer(reader.readLine(), " ");
        return st.nextToken();
    }
}
