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

long long gcd(long long x, long long y)
{
    if (y == 0)
        return x;
    return gcd(y, x % y);
}

long long lcm(long long x, long long y)
{
    if (x == 0 || y == 0)
        return 0;
    return x / gcd(x, y) * y;
}

int main()
{
    vector<vector<int>> HW(201);
    map<pair<int, int>, char> mp;
    for (int i = 0; i < 3; i++)
    {
        int H, W;
        cin >> H >> W;
        HW[H].push_back(W);
        mp[pair<int, int>(H, W)] = 'A' + i;
    }

    for (int i = 200; i > 149; i--)
    {
        if (HW[i].size() > 0)
        {
            sort(HW[i].begin(), HW[i].end());
            int n = HW[i].size();
            for (int j = 0; j < n; j++)
            {
                cout << mp[pair<int, int>(i, HW[i][j])] << endl;
            }
        }
    }
}