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.PrintWriter;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.Collection;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class A92 implements Runnable{
        
    public static void main(String args[]){
       new A92().run();
    }
    
    @Override
    public void run(){
        try{
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            tok = null;
            solve();
            in.close();
            out.close();
            
        }
        catch(IOException e){
            e.printStackTrace();
            System.exit(0);
        }
    }
    
    int nextInt()throws IOException{
        return Integer.parseInt(nextToken());
    } 
    
    double nextDouble()throws IOException{
        return Double.parseDouble(nextToken());
    }
    
    long nextLong() throws IOException{
        return Long.parseLong(nextToken());
    }
    
    String nextToken()throws IOException{
        while(tok == null || !tok.hasMoreTokens()){
            tok = new StringTokenizer(in.readLine());
        }
        return tok.nextToken();
    }
    
    BufferedReader in;
    PrintWriter out;
    StringTokenizer tok;
    //////////////////////////////////////////////////////////////////
    //////////////////////////////////////////////////////////////////
    private void solve()throws IOException{
        int n = nextInt();
        //boolean[] pos = new boolean[n + 1];
        int f = nextInt();
        int b = nextInt();
        if(n - f > b + 1)out.println(b + 1);
        else out.println(n - f);
    }
}
