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.reflect.Array;
import java.sql.Date;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class PositionsCount {

	public static int[] getArray(int size) {
		int[] array = new int[size];
		for (int i = 0; i < size; i++) {
			array[i] = sr.nextInt();
		}
		return array;
	}

	public static int[][] getMatrix(int sizeI, int sizeJ) {
		int[][] array = new int[sizeI][sizeJ];
		for (int i = 0; i < sizeI; i++) {
			for (int j = 0; j < sizeJ; j++) {
				array[i][j] = sr.nextInt();
			}
		}
		return array;
	}

	static Scanner sr = new Scanner(System.in);

	public static void main(String[] args) {

		int fullSize = sr.nextInt();
		int preCount = sr.nextInt();
		int postCount = sr.nextInt();
		int preCurrent = 0;
		int postCurrent = 0;
		int result = 0;
		for (int i = 1; i <= fullSize; i++) {
			preCurrent = i -1;
			postCurrent = fullSize - i;
			if(preCurrent >= preCount && postCurrent <= postCount) result++;
		}
		System.out.println(result);
	}
}