Compact the List

Given a strictly increasing list of integers, output each maximal run of consecutive integers as a to b, and output a single-element run as just that element. Runs keep their original order.

输入格式

The first line contains n, followed by n strictly increasing integers. The original gave no numeric bounds; this site adds 0≤n≤100000 and −10^9≤a[i]≤10^9. An empty list produces empty output text.

输出格式

Output one line per maximal consecutive run: a single item is written as a, and two or more items as a to b. An empty list produces empty output text.

样例 1

输入：

7
1 2 3 6 8 9 10

输出：

1 to 3
6
8 to 10

样例 2

输入：

4
-2 -1 0 2

输出：

-2 to 0
2

样例 3

输入：

0

输出：

样例说明

The outputs of the three public examples are, in order: 1 to 3 / 6 / 8 to 10; -2 to 0 / 2; empty text. Verified by independent enumeration or direct simulation.