#!/usr/bin/perl

while ($line  = <STDIN>) {
  chomp $line;
  $line =~ tr/a-z/A-Z/;
  @lets = split '', $line;
  $sum = 0;
  foreach (@lets) {
    $sum += ord($_) - ord ('A') + 1;
  }
  $sum %= 26;
  $sum = 26 if ($sum == 0);
  print chr($sum + ord('A') - 1);
  print "\n";
}