#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {

	int N;
	cin >> N;

	vector<int> D(N);
	for (int i = 0; i < N; i++) {
		cin >> D[i];
	}
	
	sort(D.begin(), D.end());
	
	string s = "";
	for (int i = 0; i < N; i++) {
		s += D[i]%26 + 'A';
	}
	
	cout << s << endl;
	
	return 0;
}