#include <stdio.h>

int main()
{
    long long int n;
    
    scanf ("%lld",&n);
    char out[100]={0};
    int i=0;
    
    n--;
    while(n>=0){
        out[i]= n%26 +'a';
        n/=26;
        i++;
        n--;
    }
    for(int j=i-1; j>=0; j--){
        printf("%c",out[j]);
    }
    return 0;
}
#include <bits/stdc++.h>
#define ll long long int
#define F(i,j,k,in) for(int i=j;i<k;i+=in)
#define DF(i,j,k,in) for(int i=j;i>=k;i-=in)
#define feach(it,l) for (auto it = l.begin(); it != l.end(); ++it)
#define fall(a) a.begin(),a.end()
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define eq equal_range
#define fs first
#define ss second
#define ins insert
#define mkp make_pair
#define endl "\n"
using namespace std;
typedef vector<ll> vll;
typedef vector<int> vin;
typedef vector<char> vch;
typedef vector<string> vst;
typedef vector<vector<ll>> vvll;
typedef vector<vector<int>> vvin;
typedef vector<pair<ll,ll>> vpll;
typedef vector<pair<int,int>> vpin;
typedef set<ll> sll;
typedef set<int> sint;
typedef set<char> sch;
typedef set<string> sst;
typedef queue<ll> qll;
typedef priority_queue<ll> pqll;
typedef queue<int> qin;
typedef priority_queue<int> pqin;
typedef map<ll,ll> mpll;
typedef map<int,int> mpin;
typedef pair<ll,ll> pll;
typedef pair<int,int> pin;
const ll MOD=1000000007;
const long double PI=3.1415926535897932384626433832795;
ll pwr(ll b,ll p){ll res=1;while(p){if(p&1) {res*=b; p--;}else{b*=b; p>>=1;}}return res;}
int main()
{
ios_base::sync_with_stdio(false) , cin.tie(NULL) , cout.tie(NULL);
ll x; cin>>x;
string ans;
while (x) {
  if (x%26) ans+=('a'+(x%26)-1);
  else {--x; ans+='z';}
  x/=26;
}
reverse (fall(ans));
cout<<ans;
return 0;
}
