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.

Sample Input

Input

3 1 1

Output

2

Input

5 2 3

Output

3

Sample Output

None

Hint

The possible positions in the first sample are: 2 and 3 (if we number the positions starting with 1).