%h = ( a=>[3,1..4], b=>[2,1..4], c=>[0..4] );;

@sortedKeys = sort{ $h{ $a }[0] <=> $h{ $b }[0] } keys %h;;

print "$_ : @{ $h{ $_ } }" for @sortedKeys;;
c : 0 1 2 3 4
b : 2 1 2 3 4
a : 3 1 2 3 4