#include <bits/stdc++.h>
using namespace std;

int main(){
    int N;
    cin >> N;
    vector<int> A(N);
    for (int& x : A) cin >> x;
    sort(A.begin(), A.end());

    string S;
    for (int x : A) S.push_back('A'+x%26);
    cout << S << endl;
}