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 math
from collections import defaultdict, Counter, deque

INF = float('inf')

def gcd(a, b):
	while b:
		a, b = b, a%b
	return a

def isPrime(n):
	if (n <= 1): 
		return False
	i = 2
	while i ** 2 <= n:
		if n % i == 0:
			return False
		i += 1
	return True

def primeFactor(n):
	if n % 2 == 0:
		return 2
	i = 3
	while (i ** 2) <= n:
		if n % i == 0:
			return i 
		i += 1
	return n

def vars():
	return map(int, input().split())

def array():
	return list(map(int, input().split()))

def main():
	n, a, b = vars()

	p = a 
	l = n - b - 1
	# print(p, l)
	print(n - max(p, l))




	

if __name__ == "__main__":
	# t = int(input())
	t = 1
	for _ in range(t):
		main()







