alp = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

def decode(str, n):
    bef = alp.find(str)
    aft = ( bef - n - 1 ) % 26
    return alp[aft]

ans = ""
inp = raw_input()
for i in xrange(len(inp)):
    ans += decode(inp[i], i)

print ans