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.lang.*;
import java.math.BigInteger;
import java.io.*;
import java.util.*;

public class Solution implements Runnable{
    public static BufferedReader br;
    public static PrintWriter out;
    public static StringTokenizer stk;
    public static boolean isStream = true;

    public static void main(String[] args) throws IOException {
    	if (isStream) {
            br = new BufferedReader(new InputStreamReader(System.in));
        } else {
            br = new BufferedReader(new FileReader("in.txt"));
        }
        out = new PrintWriter(System.out);
        new Thread(new Solution()).start();
    }

    public void loadLine() {
        try {
            stk = new StringTokenizer(br.readLine());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

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

    public String nextWord() {
        while (stk==null||!stk.hasMoreTokens()) loadLine();
        return stk.nextToken();
    }

    public Integer nextInt() {
        while (stk==null||!stk.hasMoreTokens()) loadLine();
        return Integer.valueOf(stk.nextToken());
    }

    public Long nextLong() {
        while (stk==null||!stk.hasMoreTokens()) loadLine();
        return Long.valueOf(stk.nextToken());
    }

    public Double nextDouble() {
        while (stk==null||!stk.hasMoreTokens()) loadLine();
        return Double.valueOf(stk.nextToken());
    }
    
    public Float nextFloat() {
        while (stk==null||!stk.hasMoreTokens()) loadLine();
        return Float.valueOf(stk.nextToken());
    }
    
    public void run() {
    	int n = nextInt();
    	int a = nextInt();
    	int b = nextInt();
    	int ans = 0;
    	for (int i = 1; i <= n; i++) {
    		if (i-1 >= a && n-i <= b) ans++;
    	}
    	out.println(ans);
    	out.flush();
    }
}
