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A8334. The number of positions

编程题 普及/提高-

题目描述

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.

输入格式

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

输出格式

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

输入输出样例

输入 #1
3 1 1
输出 #1
2
输入 #2
5 2 3
输出 #2
3

说明/提示

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.
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