Problem:
Score : 300 points

Problem Statement

1000000000000001 dogs suddenly appeared under the roof of Roger's house, all of which he decided to keep. The dogs had been numbered 1 through 1000000000000001, but he gave them new names, as follows:

the dogs numbered 1,2,\cdots,26 were respectively given the names a, b, ..., z;

the dogs numbered 27,28,29,\cdots,701,702 were respectively given the names aa, ab, ac, ..., zy, zz;

the dogs numbered 703,704,705,\cdots,18277,18278 were respectively given the names aaa, aab, aac, ..., zzy, zzz;

the dogs numbered 18279,18280,18281,\cdots,475253,475254 were respectively given the names aaaa, aaab, aaac, ..., zzzy, zzzz;

the dogs numbered 475255,475256,\cdots were respectively given the names aaaaa, aaaab, ...;

and so on.

To sum it up, the dogs numbered 1, 2, \cdots were respectively given the following names:

a, b, ..., z, aa, ab, ..., az, ba, bb, ..., bz, ..., za, zb, ..., zz, aaa, aab, ..., aaz, aba, abb, ..., abz, ..., zzz, aaaa, ...

Now, Roger asks you:

"What is the name for the dog numbered N?"

Constraints

N is an integer.

1 \leq N \leq 1000000000000001

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer to Roger's question as a string consisting of lowercase English letters.

Sample Input 1

2

Sample Output 1

b

Sample Input 2

27

Sample Output 2

aa

Sample Input 3

123456789

Sample Output 3

jjddja

Solution in C++ (GCC 9.2.1) (judge verdict: Accepted)

/*{{{*/
#include "bits/stdc++.h"
using namespace std;

#define MT make_tuple
#define all(x) begin(x), end(x)
#define putchar(x) cout << (x)
static int fastio = [](){ ios_base::sync_with_stdio(false); cin.tie(0); cout.precision(17); return 0; }();
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

template<typename ...T> string format(const string& fmt, T&&... args) {
    size_t sz = snprintf(nullptr, 0, fmt.c_str(), args...) + 1;
    unique_ptr<char[]> buf(new char[sz]);
    snprintf(buf.get(), sz, fmt.c_str(), args...);
    return string(buf.get(), buf.get() + sz - 1);
}

template<class T> struct rge { T b, e; auto begin() const { return b; } auto end() const { return e; } };
template<class T> rge<T> range(T i, T j) { return rge<T>{i, j}; }
template<class T> auto dud(T* x) -> decltype(cerr << *x, 0);
template<class T> char dud(...);

struct debug {
#ifdef LOCAL
    debug(int line) {
        if(line) cerr << "LINE(" << line << ") -> ";
    }
    template<class T> typename enable_if<sizeof dud<T>(0) != 1, debug&>::type operator<<(T i) {
        cerr << boolalpha << i; return * this;
    }
    template<class T> typename enable_if<sizeof dud<T>(0) == 1, debug&>::type operator<<(T i) {
        return *this << range(begin(i), end(i));
    }
    template<class T, class U> debug& operator<<(pair<T, U> d) {
        return *this << "(" << d.first << ", " << d.second << ")";
    }
    debug& operator<<(tuple<>&) { return *this << "()"; };
    template<class ...T> debug& operator<<(tuple<T...> d) {
        *this << "("; debug_tuple<sizeof...(T), 0>(d);
        return *this << ")";
    }
    template<size_t L, size_t I, class T> void debug_tuple(const T& t) {
        *this << (I == 0 ? "" : ", ") << get<I>(t);
        if(I + 1 < L) debug_tuple<L, (I + 1) % L>(t);
    }
    template<class T> debug & operator <<(rge<T> d) {
        *this << "[";
        for(auto it = d.b; it != d.e; ++it)
            *this << (it != d.b ?  ", " : "") << *it;
        return *this << "]";
    }
    debug& operator<<(ostream&(*pf)(std::ostream&)) {
        cerr << pf; return *this;
    }
#else
    debug(int) {}
    template<class T> debug& operator<<(T&&) { return *this; }
    debug& operator<<(ostream&(*)(std::ostream&)) { return *this; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ << ": " << (__VA_ARGS__) << "] "

#define debug0()  debug(__LINE__)
#define debug1(x) debug(0)
#define GET_MACRO(_0, _1, NAME, ...) NAME
#define debug(...) GET_MACRO(_0, ##__VA_ARGS__, debug1, debug0)(__VA_ARGS__)
/*}}}*/
using LL = long long;

const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
const LL LLINF = 0x3f3f3f3f3f3f3f3f;
const int MAX_N = 200005;

void solve(int) {
    LL N;
    cin >> N;
    string ans;
    while(N > 0) {
        N -= 1;
        ans.push_back('a' + N % 26);
        N /= 26;
    }
    reverse(all(ans));
    cout << ans << endl;
}

int main() {
    int T = 1;
    //cin >> T;
    for(int i = 1; i <= T; ++i) {
        solve(i);
    }
    return 0;
}