#include<bits/stdc++.h>
using namespace std;
string s;
ifstream f1("excel.in");
ofstream f2("excel.out");
void COUT(int i){
    while(--i>=0)f2 << s[i];
    f2 << endl;
}
int main(){
    unsigned long long n, ost, i=0;
    f1 >> n;
    while(n){
        i++;
        ost = n%26;
        if(ost==0)ost=26;
        s+=char('A'+ost-1);
        if(n%26==0)n--;
        if(n/26==1 && n%26!=0)n=1;
        else if(n/26==1){COUT(i); return 0;}
        else {n/=26;}
    }
    COUT(i);
    return 0;
}