import std;

alias sread = () => readln.chomp();
alias lread = () => readln.chomp.to!long();
alias aryread(T = long) = () => readln.split.to!(T[]);
//aryread!string();
//auto PS = new Tuple!(long,string)[](M);
//x[]=1;でlong[]全要素1に初期化
void main()
{
    auto n = lread();
    string ans = "";
    // writeln(ans);
    // writeln(cast(char)('a' + 25));
    // writeln(cast(char)('a' + n % 26));
    while (n > 0)
    {
        n -= 1;
        ans ~= cast(char)('a' + n % 26);
        n /= 26;
    }
    // writeln(ans);
    foreach_reverse (e; 0 .. (ans.length))
    {
        write(ans[e]);
    }
    writeln();

}

void scan(L...)(ref L A)
{
    auto l = readln.split;
    foreach (i, T; L)
    {
        A[i] = l[i].to!T;
    }
}

void arywrite(T)(T a)
{
    a.map!text.join(' ').writeln;
}
