Description

[IPv6 Format]

In binary, an IPv6 address is $128$ bits long. It is divided into groups of $16$ bits, separated by colons “:”, making $8$ groups in total. Each group is written as a 4-digit hexadecimal number.

For example, 2001:0db8:0000:0000:0123:4567:89ab:cdef is a valid IPv6 address.

IPv6 addresses can be compressed under certain conditions:

1. Leading zeros in each group can be omitted.

For example, the address above can be compressed to 2001:db8:0:0:123:4567:89ab:cdef.

2. A double colon :: can represent one or more consecutive groups of 0, but it can only appear once.

For example, the address above can be compressed to 2001:db8::123:4567:89ab:cdef.

Please help the forgetful network engineer Xiaoming solve his problem.

[Supplementary Rules]

1. The input is a fully expanded IPv6 address. It is guaranteed that the input IPv6 address contains no double colon, and that any omitted zeros in each group have been filled.

2. Since :: can be used only once, compress the longest run of all-zero groups.

For example, 2001:0db8:0000:0000:1:0000:0000:0000 is compressed to 2001:db8:0:0:1::, not 2001:db8::1:0:0:0.

3. Since :: can be used only once, if there are multiple runs of all-zero groups with the same maximum length, compress the earliest one.

For example, 2001:0db8:0000:0000:ffff:0000:0000:1 is compressed to 2001:db8::ffff:0:0:1, not 2001:db8:0:0:ffff::1.

4. The input IPv6 address may not be compressible. In that case, output it as-is.

Tip: The compression rules shown in this problem match the default IPv6 display style on macOS (Darwin), whereas Windows and Linux do not use :: when there is only a single all-zero group. However, IPv6 addresses compressed in this way can still be correctly recognized by Windows and Linux.

For example, 2001:0db8:ffff:0000:0123:4567:89ab:cdef is compressed by Darwin as 2001:db8:ffff::123:4567:89ab:cdef, while Linux and Windows compress it as 2001:db8:ffff:0:123:4567:89ab:cdef.

Input Format

A string of $39$ characters representing a fully expanded IPv6 address.

Output Format

A string representing the compressed IPv6 address.

2406:0840:f990:0000:0000:0000:0000:0001

2406:840:f990::1

2a13:1801:018a:00cf:0100:0000:0000:0000

2a13:1801:18a:cf:100::

2001:4860:4860:0000:0000:0000:0000:8888

2001:4860:4860::8888

2001:0db8:0000:0000:0000:0000:0000:0001

2001:db8::1

0000:0000:0000:0000:0000:0000:0000:0000

::

0000:0000:0000:0000:0000:0000:0000:0001

::1

2001:0db8:ffff:0000:0123:4567:89ab:cdef

2001:db8:ffff::123:4567:89ab:cdef

1234:5678:9abc:def0:1234:5678:9abc:def0

1234:5678:9abc:def0:1234:5678:9abc:def0

0001:0000:0000:0000:0000:0000:0000:0001

1::1

0000:0000:0000:0000:0000:0000:0001:0002

::1:2

Hint

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