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.
#!/usr/bin/env python

l = raw_input()
i1 = l.index(' ')
n = int(l[:i1])
i2 = l.index(' ', i1+1)
a = int(l[i1+1:i2])
b = int(l[i2+1:])

cnt = 0
for i in range(a, n):
    for j in range(0, b + 1):
        if i + j + 1 == n:
            cnt += 1
print cnt
