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.*;
import java.math.*;

public class Solution {

    private BufferedReader in;
    private PrintWriter out;
    private StringTokenizer st;

    public String next() throws Exception {
        if (st == null || !st.hasMoreElements()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }

    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }

    public void run() throws Exception {
        in = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
        int n = nextInt();
        int a = nextInt();
        int b = nextInt();
        int ans = 0;
        for (int i = 0; i < n; ++i) {
            if (i >= a && (n - i - 1) <= b) ans++;
        }
        out.println(ans);
        out.close();
    }

    public static void main(String[] args) throws Exception {
        new Solution().run();
    }
}
