bef = IO.read(__FILE__)
aft = $<.read
STDERR.puts "bef:"
STDERR.puts bef
STDERR.puts "aft:"
STDERR.puts aft
bef.chars.zip(aft.chars).each_with_index do |cc,i|
    if cc[0] != cc[1]
        p i
        puts '"'+cc[0]+'"'
        puts '"'+cc[1]+'"'
        exit
    end
end