Problem

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成对排列

Problem

给定一个数 N (\(2<=N<=20\), N-even) - 数组元素的数量。编写一个程序，交换给定数组的元素对。也就是第一个配第二个，第三个配第四个，等等

输入
第一行包含数字N——数组元素的个数。 第二行包含数组元素的值。

印记
您需要显示结果数组。
 
例子
<头> <正文>

time 1000 ms
memory 32 Mb
Rules for program design and list of errors in automatic problem checking

Teacher commentary

Your Program

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# 输入 输出
1 4
1 2 3 4 		2 1 4 3