#A. 数车厢

Type: Default

1000ms

256MiB

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题目背景

五一放假了, 辰辰要坐火车回姥姥家

火车一共有 $n$ 节车厢, 辰辰在火车从前向后数第 $a$ 节车厢, 请问从后向前数, 这是第几节车厢?

一行两个整数 $n, a$ .

输出一个整数, 表示从后向前数, 这是第几节车厢.

5 3

2 1

$1 \leq a \leq n \leq 100$