local n=io.read("n")
local t={}
while n>0 do
    local mod=n%26
    if mod==0 then
        mod=26
    end
    table.insert(t,mod+96)
    n=n-mod
    n=n//26
end

local answer={}
for i=#t,1,-1 do
    table.insert(answer,string.char(t[i]))
end
print(table.concat(answer,""))