use strict;
use warnings;
use v5.16;

# my $input = "ABCdef";
my $input = <>;
chomp $input;

my @a = split //, $input;

my $output = "";
for (@a){
    if ($_ =~ /[a-z]/){
        $output .= uc($_);
    }else{
        $output .= lc($_);
    };
}
say $output;