#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (int)(n); i++)

using namespace std;

int main(){
    int N;
    cin >> N;
    vector<int> A(N);
    rep(i,N) cin >> A[i];
    int m = -1, v = 0;
    rep(i,500){
        if(abs(A[i]) > v){
            v = abs(A[i]);
            m = i;
        }
    }
    
    string code[7] = {"C4", "D4", "E4", "F4", "G4", "A4", "B4"};
    int f[7] = {2616, 2943, 3270, 3488, 3924, 4360, 4905};
    int max_sum[7] = {0};
    
    rep(i,7){
        rep(j,8){
            int p = m + j * f[i];
            max_sum[i] += abs(A[p]);
        }
    }
    int ans = -1, res = 0;
    rep(i,7){
        if(max_sum[i] > res){
            res = max_sum[i];
            ans = i;
        }
    }
    cout << code[ans] << endl;
    
    return 0;
}