#include <cstdio>
#include <algorithm>
#include <queue>
using namespace std;

const int MAXN = 505;

int N, conn [MAXN][2], how [MAXN][MAXN];
bool vis [MAXN][MAXN];

void bfs ()
{
    queue <pair <int, int> > q;
    q.push (make_pair (0, 0));
    vis [0][0] = true;

    while (!q.empty ())
    {
        pair <int, int> top = q.front (); q.pop ();

        for (int i = 0; i < 2; i++)
            for (int a = 0; a < N; a++)
                if (conn [a][i] == top.first)
                    for (int b = 0; b < N; b++)
                        if (conn [b][i] == top.second && !vis [a][b])
                        {
                            vis [a][b] = true;
                            how [a][b] = i;
                            q.push (make_pair (a, b));
                        }
    }
}

int main (void)
{
    scanf ("%d", &N);

    for (int i = 0; i < N; i++)
        for (int j = 0; j < 2; j++)
        {
            scanf ("%d", &conn [i][j]);
            conn [i][j]--;
        }

    bfs ();

    vector <int> st;

    for (int i = 0; i < N; i++)
        st.push_back (i);

    while (st.size () > 1)
    {
        pair <int, int> p (st [0], st [1]);

        while (p != make_pair (0, 0))
        {
            int h = how [p.first][p.second];
            putchar ('A' + h);

            for (int i = 0; i < (int) st.size (); i++)
                st [i] = conn [st [i]][h];

            p = make_pair (conn [p.first][h], conn [p.second][h]);
        }

        sort (st.begin (), st.end ());
        st.resize (unique (st.begin (), st.end ()) - st.begin ());
    }

    putchar ('\n');

    return 0;
}