#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int main(){
	vector<string> s = {"C4", "D4", "E4", "F4", "G4", "A4", "B4"};
	vector<double> d = {261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5};
	
	int n;
	cin>>n;
	vector<int> a(n);
	rep(i,n)cin>>a[i];
	
	int ans = -1;
	int D = Inf;
	
	rep(i,d.size()){
		int NN = n;
		NN /= (int)round(d[i]);
		vector<int> b = a;
		rep(j,NN){
			b.push_back(b[0]);
			b.erase(b.begin());
		}
		int sum = 0;
		rep(j,b.size())sum += abs(b[j] - a[j]);
		if(D > sum){
			D = sum;
			ans = i;
		}
		
	}
	
	cout<<s[ans]<<endl;
	
	return 0;
}