my $last = ""; while () { my (undef,$number,$item,$rest) = split /\s+/, $_, 4; my $current_two_letters = substr($item,0,2); if ($current_two_letters ne $last) { print "--- Break here (change from $last to $current_two_letters)\n"; }; print $_; $last = $current_two_letters; }; __DATA__ 1930: Nails <-- #Na here 1931: Naked 1941: Nearsighted <-- #Ne here 1942: Neck 1961: Newspaper_Reporter 1963: Nickname <-- #Ni here 1964: Niece 1971: Nipples 1972: Nobility <-- #No here 1973: Noise 1981: November 1982: Nuclear_Bomb <-- #Nu here 1984: Numbers 1989: Nuts 1990: Nymph