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.*;
import java.util.StringTokenizer;

public class Positions implements Runnable {

        void solve() throws IOException {
        	int n = nextInt();
        	int a = nextInt();
        	int b = nextInt();

        	int count = 0;
        	for(int i=a+1;i<=n;i++){
        		if(n-i<=b)
        			count++;
        	}
        	writer.println(count);
         }

        BufferedReader reader;
        StringTokenizer tokenizer;
        PrintWriter writer;

        public void run() {
            try {
                reader = new BufferedReader(new InputStreamReader(System.in));
                writer = new PrintWriter(System.out);
                //reader = new BufferedReader(new FileReader("input.txt"));
                //writer = new PrintWriter(new BufferedWriter(new FileWriter("output.txt")));
                tokenizer = null;
                solve();
                reader.close();
                writer.close();
            } catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
            }
        }

        int nextInt() throws IOException {
            return Integer.parseInt(nextToken());
        }

        long nextLong() throws IOException {
            return Long.parseLong(nextToken());
        }

        double nextDouble() throws IOException {
            return Double.parseDouble(nextToken());
        }

        String nextToken() throws IOException {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                tokenizer = new StringTokenizer(reader.readLine());
            }
            return tokenizer.nextToken();
        }

        public static void main(String[] args) {
                new Positions().run();
        }

}
