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.ArrayList;
import java.util.Arrays;
import java.util.StringTokenizer;

public class CF124A {
    public static void main(String[] args) {
        FastReader input = new FastReader();
        PrintWriter pw = new PrintWriter(System.out);


        int n = input.nextInt();
        int a = input.nextInt();
        int b = input.nextInt();
        char[] arr = new char[n];

        Arrays.fill(arr,'d');

        for(int i = 0;i < a;i++){
            arr[i] = 'x';
        }
        arr[a] = 'c';
        int next = a+1;
        for(int i = 0;i < b;i++){
            int index = next + i;
            if(index >= arr.length){
                break;
            }
            else {
                arr[index] = 'p';
            }
        }

        int count = 0;

        for(int i = 0;i < n;i++){
            if(arr[i] == 'c' || arr[i] == 'p'){
                count++;
            }
        }
        pw.println(count);

        pw.flush();
        pw.close();
    }
    static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

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

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

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

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