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.

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.