#include <algorithm>
#include <iostream>
#include <numeric>
#include <vector>
#include <bitset>
#include <set>
#include <map>
typedef long long llong;
const int MAXN = 1000000 + 10;
const int INF = 1e9;
int a[MAXN][2], n;
int dpA[MAXN][2];
int dpB[MAXN][2];
char ans[MAXN];
void solve()
{
for (int i = 1 ; i <= 2*n ; ++i)
{
dpA[i][0] = dpB[i][0] = -INF;
dpA[i][1] = dpB[i][1] = -INF;
for (int last = 0 ; last <= 1 ; ++last)
{
if (a[i][0] >= a[i - 1][last])
{
dpA[i][0] = std::max(dpA[i][0], dpA[i - 1][last] + 1);
dpB[i][0] = std::max(dpB[i][0], dpB[i - 1][last]);
}
if (a[i][1] >= a[i - 1][last])
{
dpA[i][1] = std::max(dpA[i][1], dpA[i - 1][last]);
dpB[i][1] = std::max(dpB[i][1], dpB[i - 1][last] + 1);
}
}
}
if (std::max(dpA[2*n][0], dpA[2*n][1]) < n || std::max(dpB[2*n][0], dpB[2*n][1]) < n)
{
std::cout << -1 << '\n';
return;
}
a[2*n + 1][0] = INF;
int cntA = n, cntB = n;
int idx = 2*n, last = 0;
while (cntA >= 1 || cntB >= 1)
{
if (a[idx][0] <= a[idx + 1][last] && dpA[idx][0] >= cntA && dpB[idx][0] >= cntB)
{
ans[idx - 1] = 'A';
last = 0;
cntA--;
idx--;
continue;
}
if (a[idx][1] <= a[idx + 1][last] && dpA[idx][1] >= cntA && dpB[idx][1] >= cntB)
{
ans[idx - 1] = 'B';
last = 1;
cntB--;
idx--;
continue;
}
std::cout << -1 << '\n';
return;
}
ans[2*n] = '\0';
std::cout << ans << '\n';
}
void read()
{
std::cin >> n;
for (int i = 1 ; i <= 2*n ; ++i) std::cin >> a[i][0];
for (int i = 1 ; i <= 2*n ; ++i) std::cin >> a[i][1];
}
void fastIO()
{
std::ios_base :: sync_with_stdio(0);
std::cout.tie(nullptr);
std::cin.tie(nullptr);
}
int main()
{
fastIO();
read();
solve();
return 0;
}
