#include<bits/stdc++.h>
using namespace std;
long long X;
vector<char>res;
int main(){

    freopen("excel.in","r",stdin);
    freopen("excel.out","w",stdout);

    cin>>X;
    int i=1;
    while(X>0){
        char a=X%26+'A'-1;
        if(a=='@')a='Z';
        //cout<<a<<endl;
        res.push_back(a);
        X-=(a-'A');
        X/=26;

    }
    for(int i=res.size()-1; i>=0; i--){
        cout<<res[i];
    }
    cout<<endl;


    return 0;
}