class Program {

	private string num2alpha(int $n) {
		string $r = '';
		for(int $i = 1; $n >= 0 && $i < 10; $i++) {
			$r = chr(0x41 + ($n % pow(26, $i) / pow(26, $i - 1))) + $r;
			$n -= pow(26, $i);
		}
		return $r;
	}

	private int alpha2num(string $a) {
		int $r = 0;
		int $l = strlen($a);
		for(int $i = 0; $i < $l; $i++) {
			$r += pow(26, $i) * (ord($a[$l - $i - 1]) - 0x40);
		}
		return (int) $r - 1;
	}

	public void main() {
		import('math');
		var_dump($this->alpha2num("Salut"), $this->num2alpha(1723), $this->num2alpha(9854), $this->alpha2num("Base64"));
	}

}