php - zoj 1115 Digital Roots

<?php
// Run Time(ms) 10
// Run Memory(KB) 212
while(fscanf(STDIN,"%s",$integer) <> NULL){
if($integer == 0){
break;
}
$arr = str_split($integer);
$rst = 0;
foreach ($arr as $key => $value){
$rst += $value % 9;
}
$rst %= 9;
$rst = $rst === 0 ? 9 : $rst;
print $rst."/n";
}