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.
def number_position():
    qty_people, in_front, behind = map( int, raw_input().split(' '))
    number_position = qty_people - in_front 

    if  number_position > behind:
        return behind + 1
    elif number_position == behind:
        return behind
    elif number_position < behind:
        return number_position


print(number_position())