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

public class Main {
    FastScanner in;
    PrintWriter out;

    public void run(Main oMain) {
        try {
            in = new FastScanner(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            solve(oMain);
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void solve(Main oMain) throws IOException {
        int n = in.nextInt();
        int a = in.nextInt();
        int b = in.nextInt();
        
        int counter = 0;
        for (int i=1; i<=n; i++) {
            if (i > a && (n - i) <= b) {
                counter++;
            }
        }
        out.println(counter);
    }

    class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        FastScanner(InputStreamReader in) {
            br = new BufferedReader(in);
        }

        String nextLine() {
            String str = null;
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }

            return str;
        }

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

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

    public static void main(String[] arg) {
        Main oMain = new Main();
        oMain.run(oMain);
    }

}
