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.
//package com.company;
import javax.swing.*;
import java.util.*;
import java.io.*;
public class Main  {
    static FastReader in=new FastReader();
    static final Random random=new Random();
    static long mod=1000000007L;
    static HashMap<Character,Integer>map=new HashMap<>();
    static HashMap<Long,Integer>ans=new HashMap<>();
    static Set<Integer> chr= new HashSet<>();
    static Set<Integer> chr1= new HashSet<>();
    static ArrayList<Integer> arl = new ArrayList<>();
    public static String sortString(String st){
        char [] c = st.toCharArray();
        Arrays.sort(c);
        return String.valueOf(c);
    }

    public static void main(String args[]) throws IOException {
        StringBuilder res = new StringBuilder();
        int n = in.nextInt();
        int a = in.nextInt();
        int b = in.nextInt();
        int max = Math.max(a+1,n-b);
        int ans = n-max+1;
        System.out.println(ans);
        
    }

    static int max(int a, int b)
    {
        if(a<b)
            return b;
        return a;
    }


    static void ruffleSort(int[] a) {
        int n=a.length;
        for (int i=0; i<n; i++) {
            int oi=random.nextInt(n), temp=a[oi];
            a[oi]=a[i]; a[i]=temp;
        }
        Arrays.sort(a);
    }

    static < E > void print(E res)
    {
        System.out.println(res);
    }


    static  int gcd(int a,int b)
    {
        if(b==0)
        {
            return a;
        }
        return gcd(b,a%b);
    }

    static int lcm(int a, int b)
    {
        return (a / gcd(a, b)) * b;
    }


    static int abs(int a)
    {
        if(a<0)
            return -1*a;
        return a;
    }

    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;
        }

        int [] readIntArray(int n) {
            int res [] = new int [n];
            for(int i = 0; i<n; i++)res[i] = nextInt();
            return res;
        }
        long [] readLongArray(int n) {
            long res [] = new long [n];
            for(int i = 0; i<n; i++)res[i] = nextLong();
            return res;
        }
    }

}