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

void solve(){
	ll N;
	cin>>N;
	vector<ll> D(N);
	for(int i=0;i<N;i++)cin>>D[i];
	sort(D.begin(),D.end());
	for(auto d:D)cout<<char(d%26+'A');
	cout<<endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
	
	ll T=1;
	// cin>>T;
	while(T--)
	solve();

}