#include <bits/stdc++.h>
#define ll long long
using namespace std;

int main() {
    ll n;cin>>n;
    string str;
    while(n!=0){
        int x=(n-1)%26;
        char ch='a'+x;
        str=ch+str;
        n=(n-1)/26;
    }
    cout<<str;
}
