#include using namespace std; #define FOR(i,a,b) for(int i=(a);i<(b);i++) #define REP(i,n) FOR(i,0,n) #define ALL(v) (v).begin(),(v).end() template inline bool chmax(A &a, B b) { if (a inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; } typedef unsigned long long ull; typedef long long ll; typedef pair pii; typedef pair pll; typedef pair P; const ll INF = 1ll<<29; const ll MOD = 1000000007; const double EPS = 1e-10; int main() { ll n; cin >> n; string ans; while (n >= 0) { ans.push_back(n % 26 + 'A'); n /= 26; n--; } reverse(ALL(ans)); cout << ans << endl; return 0; }