$cities = "cities.txt"; 	  # number/letters - city correspondences
$cities_st = "cities_st.txt"; # city standard file
$tmp = "temp.txt";            # temp file to keep the password

# choose random letters or numbers

@array = (0..9,a..z,A..Z);
srand;
foreach (1..5) {    
	$rand = int(rand scalar(@array));    
	push (@selected, $rand);
}

# save the chosen password to file

open TMP, ">$tmp";
print TMP @selected;
close TMP;

# open file with number/letter - cities correspondences

open CITIES, $cities;
while (<CITIES>) {
	for ($x; $x<5; $x++) {
		$match = $selected[$x];
		if (/\+$match\+(\w+)/) {$selected[$x] = $1;}
	}
}
close CITIES;

# erase file with number/letter - city correspondences

unlink $cities;

# read "cities_st.txt"

open CITIES_ST, $cities_st;
while (<CITIES_ST>) {
	/(\w+)/;
	push (@cities, $1);
}
close CITIES_ST;

# randomize cities

foreach (0..99) {
	$rand = int(rand scalar(@cities));
	splice (@cities, $rand, 1);
	push (@cities, $_);
}

# create new "cities.txt"

open CITIES, ">$cities";
foreach (a..z) {
	$city = 0;
	$out = "+",$_,"+",$cities[$city];
	$city++;
	print CITIES $out;
}
foreach (A..Z) {
	$city = 26;
	$out = "+",$_,"+",$cities[$city];
	$city++;
	print CITIES $out;
}
foreach (0..9) {
	$city = 51;
	$out = "+",$_,"+",$cities[$city];
	$city++;
	print CITIES $out;
}
close CITIES;

# print the html code

for ($i; $i<5; $i++){
    print "<img src='image_dir/$selected[$i].jpg' border=0>";
}