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: Wrong Answer)

#include <bits/stdc++.h>
#include <math.h>
#define ALL(a)    a.begin(), a.end()
using namespace std;

vector<int> V;

void f(int N){
int M;
M = N;
int i = 0;

while(pow(26, i) <= N){
V.push_back(M%26);
M /= 26;
i++;}

return;}


int main() {
unsigned long long int N, n;cin >> N;

for(int i = 1; i < 12; i++){
if((pow(26, i) - 1)/25 <= N &&
   N < (pow(26, i + 1) - 1)/25){
n = i;break;}}

f(N - (pow(26, n) - 1)/25);
V.resize(n); reverse(ALL(V));

for(long long int i = 0; i < n; i++){

if(V[i] == 0)cout << 'a';
if(V[i] == 1)cout << 'b';
if(V[i] == 2)cout << 'c';
if(V[i] == 3)cout << 'd';
if(V[i] == 4)cout << 'e';
if(V[i] == 5)cout << 'f';
if(V[i] == 6)cout << 'g';
if(V[i] == 7)cout << 'h';
if(V[i] == 8)cout << 'i';
if(V[i] == 9)cout << 'j';
if(V[i] == 10)cout << 'k';
if(V[i] == 11)cout << 'l';
if(V[i] == 12)cout << 'm';
if(V[i] == 13)cout << 'n';
if(V[i] == 14)cout << 'o';
if(V[i] == 15)cout << 'p';
if(V[i] == 16)cout << 'q';
if(V[i] == 17)cout << 'r';
if(V[i] == 18)cout << 's';
if(V[i] == 19)cout << 't';
if(V[i] == 20)cout << 'u';
if(V[i] == 21)cout << 'v';
if(V[i] == 22)cout << 'w';
if(V[i] == 23)cout << 'x';
if(V[i] == 24)cout << 'y';
if(V[i] == 25)cout << 'z';

}
}