s = input()

s_list = list(s)
#print(s, s_list)

if "y" not in s_list:
    print("y")
elif "u" not in s_list:
    print("u") 
elif "k" not in s_list:
    print("k")
elif "i" not in s_list:
    print("i")
elif "c" not in s_list:
    print("c")
elif "o" not in s_list:
    print("o") 
elif "d" not in s_list:
    print("d") 
elif "e" not in s_list:
    print("e")
elif "r" not in s_list:
    print("r")