#include typedef long long ll; using namespace std; int INF = 1e9; int MOD = 1e9+7; main(){ int N; cin >> N; N++; string s; for(;N>=1;N/=26){ char c = ((N+25)%26+'A'); if(c == 'Z')N-=26; s = c + s; } cout << s << endl; }