#!/usr/bin/perl

# http://perlmonks.org/?node_id=1211586

use strict;
use warnings;

$_ = do { local $/; <DATA> };

s/:\w+:/:/g;
1 while s/^(\w+):[\d:]*\K(\n.*?)^\1(:\d+)\n/$3$2/gsm;

print;

__DATA__
China:wd:2
Japan:wd:6
China:sg:2
Japan:sg:10
China:kng:70
Thailand:kng:6
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