s = input().strip()
result = []
for idx in range(len(s)):
    c = s[idx]
    shift = idx + 1  # 1-based index
    original_ord = ord(c) - ord('A')
    new_ord = (original_ord - shift) % 26
    result.append(chr(new_ord + ord('A')))
print(''.join(result))