print "In this version you can use up to TEN NUMBERS! \n";
print "when you have entered the numbers you need type 'end' \n";

print "Enter number 1 ";
my $num1 = <STDIN>;

print "Enter number 2 ";
my $num2 = <STDIN>;

print "Enter number 3 ";
my $num3 = <STDIN>;

if ($num3 =~ /^[+-]?\d+$/ ) {
    print "Enter number 4 ";
    my $num4 = <STDIN>;
    
    if ($num4 =~ /^[+-]?\d+$/ ) {
        print "Enter number 5 ";
        my $num5 = <STDIN>;
        
            if ($num5 =~ /^[+-]?\d+$/ ) {
            print "Enter number 6 ";
            my $num6 = <STDIN>;
            
                if ($num6 =~ /^[+-]?\d+$/ ) {
                    print "Enter number 7 ";
                    my $num7 = <STDIN>;
                    
                    if ($num7 =~ /^[+-]?\d+$/ ) {
                        print "Enter number 8 ";
                        my $num8 = <STDIN>;
                        
                        if ($num8 =~ /^[+-]?\d+$/ ) {
                            print "Enter number 9 ";
                            my $num9 = <STDIN>;
                            
                            if ($num9 =~ /^[+-]?\d+$/ ) {
                                print "Enter number 10 ";
                                my $num10 = <STDIN>;
                                
                                if ($num10 =~ /^[+-]?\d+$/ ) {
                                    print "Your answer is " . (($num1+$num2+$num3+$num4+$num4+$num5+$num6+$num7+$num8+$num9+$num10)/10) . "\n";

                                } else {
                                    print "Your answer is " . (($num1+$num2+$num3+$num4+$num5+$num6+$num7+$num8+$num9)/9) . "\n";
                                }
                            } else {
                                print "Your answer is " . (($num1+$num2+$num3+$num4+$num5+$num6+$num7+$num8)/8) . "\n";
                            }
                        } else {
                            print "Your answer is " . (($num1+$num2+$num3+$num4+$num5+$num6+$num7)/7) . "\n";
                        }
                    } else {
                        print "Your answer is " . (($num1+$num2+$num3+$num4+$num5+$num6)/6) . "\n";
                    }
                } else {
                    print "Your answer is " . (($num1+$num2+$num3+$num4+$$num5)/5) . "\n";
                }
        } else {
            print "Your answer is " . (($num1+$num2+$num3+$num4)/4) . "\n";
        }
    } else {
        print "Your answer is " . (($num1+$num2+$num3)/3) . "\n";
    }
} else {
    print "Your answer is " . (($num1+$num2)/2) . "\n";
}