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.
a,b,c = map(int,input().split())
k = 1
if c == 0 or a == 0:
	print(1)
	exit()
if b + c + k == a:
	print(c+1)
elif b + c+ k < a:
	b = a - c - 1
	print(c+1)
elif b + c +k > a:
	c = a -(b+1)
	print(c+1)
	

	
