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

using ll = long long;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	int N;
	cin >> N;
	vector<int> d(N), a(N);
	rep(i, N) cin >> d[i];
	sort(d.begin(), d.end());
	rep(i, N) a[i] = d[i] % 26;
	string s;
	rep(i, N) s += (char)(a[i] + 'A');
	cout << s << endl;
}