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.
from sys import stdin
rr = lambda: stdin.readline().strip()
rri = lambda: int(rr())
rrm = lambda: map(int, rr().split())
def rry(N = None, f = rri):
    for i in xrange(N or rri()):
        yield f()

N,A,B = rrm()
ans = 0
for i in xrange(1, 1+N):
	num_in_front = i-1
	num_behind = N-i
	if num_in_front >= A and num_behind <= B:
		ans += 1
print ans