local N = io.read("*n")
local abc = "abcdefghijklmnopqrstuvwxyz"

local N_to_0_num = N
local str = ""
while N_to_0_num > 0 do
	local index = N_to_0_num%26
	str = str..abc:sub(index, index)
	N_to_0_num = N_to_0_num // 26
end

print(str:reverse())
