use Set::Infinite;

my @array = (
    ['NM_144963','2713','4091'],
    ['NM_144963','1949','2712']
);

my $set = Set::Infinite->new->integer;
$set = $set->union( $_->[1], $_->[2] ) for @array;
print "Set: $set, Size: ",$set->size," Length: ",$set->span->size,"\n";
# Set: [1949..4091], Size: 2142 Length: 2142

@array = (
    ['NM_176827','618','710'],
    ['NM_176827','621','710'],
    ['NM_176827','622','692'],
    ['NM_176827','629','710']
);

$set = Set::Infinite->new->integer;
$set = $set->union( $_->[1], $_->[2] ) for @array;
print "Set: $set, Size: ",$set->size," Length: ",$set->span->size,"\n";
# Set: [618..710], Size: 92 Length: 92