One pattern you can apply for that kind of thing is:

my $answer = 42;
while (1) {
    print "What is the answer? ";
    chomp( my $input = <STDIN> );
    if ( $input == $answer ) {
        print "Good!\n";
        last;  # break out of innermost loop
    }
    else {
        print "Please try again.\n";
    }
}
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