#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;
ll x;
string s = "ZABCDEFGHIJKLMNOPQRSTUVWXYZ";
string ans;

int main(void){
    scanf("%lld", &x);
    while(x){
        ans += s[x % 26];
        x = (x - ((x % 26) + 26) % 27) / 26;
        /*if(x % 26 == 0) x = (x - 26) / 26;
        else x = (x - x % 26) / 26;*/
    }
    reverse(ans.begin(), ans.end());
    cout << ans << endl;
    return 0;
}