#include <iostream>
#include <iomanip>
#include <cstdio>
#include <queue>
#include <cstring>
#include <vector>
#include <map>
#include <algorithm>
#include <cctype>
#include <cmath>
#include <bitset>
#include <set>
#include <stack>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define RREP(i,n) for(int i=n-1;i>=0;i--)
#define FOR(i,k,n) for(int i=(k);i<(int)(n);i++)
#define all(i,n) (i),(i+n)

int dx4[4]={1,0,-1,0};
int dy4[4]={0,-1,0,1};
int dx8[8]={1,0,-1,1,-1,1,0,-1};
int dy8[8]={1,1,1,0,0,-1,-1,-1};
int dx9[9]={0,1,0,-1,1,-1,1,0,-1};
int dy9[9]={0,1,1,1,0,0,-1,-1,-1};

typedef pair<int, int> P;
typedef pair<string, int> SP;
typedef long long ll;
typedef pair<ll, ll> PLL;

const int INF = 1e9;
const ll LLINF = 1e18;
const int MAX_V = 1e6+1;
const ll mod = 1000000007;

// --------------------------------------
ll n;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  cin >> n;

  int b[50], i = 0;
  if(n == 0) {
    b[i] = 0;
    i++;
  }
  for(; n > 0; i++) {
    b[i] = n % 26;
    n /= 26;
  }

  RREP(j, i) {
    if(i > 1 && i - 1 == j) cout << (char)(b[--i] + 64);
    else cout << (char)(b[--i] + 65);
  }

  cout << endl;
}