1094:The number of positions

Time/Memory Limit:1000 MS/32768 K
Submitted: 162 Accepted: 67

 Problem Description

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.


The only line contains three integers n, a and b (0<=a,b<n<=100).


Print the single number — the number of the sought positions.

 Sample Input

3 1 1

 Sample Output