#!/usr/bin/perl
       use warnings;
       use strict;
       while(<STDIN>) {
               print, next unless /\S/;
               my $inpara = $_;
               my $nextline;
               while(1) {
                       $nextline = <STDIN>;
                       $nextline = "" unless defined $nextline;
                       last unless $nextline =~ /\S/;
                       $inpara .= $nextline;
               }
               $inpara =~ s/\n\z//;
               $inpara =~ s/\t/        /g;
               $inpara =~ /(?:\A|\n)( *)[^\n]*\z/;
               my $prefix = $1;
               $inpara =~ s/([.!?])\n\s*/$1  /g;
               $inpara =~ s/\n\s*/ /g;
               my $outpara = "";
               while($inpara !~ /\A *\z/) {
                       $inpara =~ s/\A(.{0,69}\S|\S{70,})(?:\z|\s+)//;
                       $outpara .= $1."\n";
                       $inpara = $prefix.$inpara;
               }
               print $outpara;
               $_ = $nextline;
               redo;
       }
       exit 0;