import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv,
    std.functional, std.math, std.numeric, std.range, std.stdio, std.string,
    std.random, std.typecons, std.container;

ulong MAX = 100_100, MOD = 1_000_000_007, INF = 1_000_000_000_000;
alias sread = () => readln.chomp();
alias lread(T = long) = () => readln.chomp.to!(T);
alias aryread(T = long) = () => readln.split.to!(T[]);
alias Pair = Tuple!(long, "a", long, "b");
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);

void main()
{
    long n = lread();
    auto alph = "abcdefghijklmnopqrstuvwxyz";
    auto k = new long[](0);
    while (n > 0)
    {
        k ~= n % 26;
        n /= 26;
    }
    // k.writeln();
    auto ans = new char[](0);
    foreach (i, e; k)
    {
        if (e)
        {
            ans ~= alph[e - 1];
        }
        else
        {
            if (i + 1 < k.length)
            {
                ans ~= 'z';
                long tmp = i + 1;
                while (k[tmp] == 0)
                {
                    k[tmp] = 25;
                    tmp++;
                }
                k[tmp]--;
            }
        }
    }
    ans.reverse().writeln();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}
