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.
#codeforces 124A
#fundphys

input = raw_input().split(" ")
n = int( input[0] )
a = int( input[1] )
b = int( input[2] )

pos = 0

for i in xrange(1, n+1):
	if (i > a) and ((n - i - 1) < b):
		pos += 1


print pos

