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.
'''
INPUT SHORTCUTS
N, K = map(int,input().split())
N ,A,B = map(int,input().split())
string = str(input())
arr = list(map(int,input().split()))
N = int(input())
'''


def main(N,a,b):
	cnt =0
	for i in range(a,N):
		# print(i)
		if ((N-1)-i)<=b:
			# print(N-1,a,b)
			cnt+=1
	print(cnt)

def text():
	with open("input.txt","r") as f:
		t = int(f.readline().rstrip())
		while t:
			N, a ,b = map(int,f.readline().rstrip().split())
			main(N,a,b)
			t-=1

def normal():
	N , a ,b = map(int,input().split())
	main(N,a,b)



# text()

normal()

