#!/usr/bin/perl

sub minimumNumber {
    $len = shift;
    $_ = shift;
    
    $need = (6 - $len);
    if ($need >= 4) { return $need;}
    $miss = 4;
    if (/\d/) {$miss--;}
    if (/[a-z]/) {$miss--;}
    if (/[A-Z]/) {$miss--;}
    if (/\!|\@|\#|\$|\%|\^|\&|\*|\(|\)|\-|\+]/) {$miss--;}
    return ($need > $miss) ? $need : $miss
    # Return the minimum number of characters to make the password strong   
}

$n = <STDIN>;
chomp $n;
$password = <STDIN>;
chomp $password;
$answer = minimumNumber($n, $password);
print "$answer\n";