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.InputStreamReader;
import java.util.StringTokenizer;


public class CF124A {

	public static void main(String[] args)throws Exception {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		for(String ln;(ln=in.readLine())!=null;){
			StringTokenizer st = new StringTokenizer(ln);
			int N = Integer.parseInt(st.nextToken());
			int A = Integer.parseInt(st.nextToken());
			int B = Integer.parseInt(st.nextToken());
			int maxIndex = Math.max(A, (N-B));
			int cont = N-maxIndex;
			if((N-B)-A>0)
				cont++;
			System.out.println(cont);
		
		}

	}
}
