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.OutputStreamWriter;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.*; 
public class TreeMapDemo { 
public static void main(String args[]) throws IOException { 
    BufferedReader k=new BufferedReader(new InputStreamReader(System.in));
    StringBuffer str=new StringBuffer();
    PrintWriter out=new PrintWriter(new OutputStreamWriter(System.out));
    StringTokenizer s=new StringTokenizer(k.readLine());
    int n=Integer.parseInt(s.nextToken());
    int m=Integer.parseInt(s.nextToken());
    int f=Integer.parseInt(s.nextToken());
    if (m+f<n) {
        out.println(f+1);
    }
    else if (m+f==n) {
        out.println(f);
    }
    else {
        out.println(n-m);
    }
//    out.println(str);
    out.close();
//    
    
    
    
} 
}



















