#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define TASK ""
#define ALL(x) (x).begin(), (x).end()
using namespace std;
template <typename T1, typename T2> bool mini(T1 &a, T2 b) {
if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maxi(T1 &a, T2 b) {
if (a < b) {a = b; return true;} return false;
}
const int N = 1e6 + 5;
const int oo = 1e9;
const long long ooo = 1e18;
const int mod = 1e9 + 7; // 998244353;
const long double pi = acos(-1);
pair <int, int> dp[N][2];
int a[N][2];
int n;
string ans;
void trace(int i, int cur, int lef) {
ans += ('A' + cur);
if (i == 1) {
reverse(ALL(ans));
return;
}
lef -= !cur;
for (int pre = 0; pre < 2; pre++) if (a[i - 1][pre] <= a[i][cur]) {
int l = dp[i - 1][pre].fi;
int r = dp[i - 1][pre].se;
if (l <= lef && lef <= r) {
trace(i - 1, pre, lef);
return;
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
#ifdef ONLINE_JUDGE
// freopen(TASK".inp","r",stdin);
// freopen(TASK".out","w",stdout);
#endif
cin >> n;
for (int j = 0; j < 2; j++)
for (int i = 1; i <= 2 * n; i++)
cin >> a[i][j];
dp[0][1] = mp(0, 0);
dp[0][0] = mp(0, 0);
for (int i = 1; i <= 2 * n; i++)
for (int j = 0; j < 2; j++)
dp[i][j] = mp(-1, -1);
for (int i = 0; i < 2 * n; i++)
for (int j = 0; j < 2; j++) {
int l = dp[i][j].fi;
int r = dp[i][j].se;
if (l < 0)
continue;
for (int k = 0; k < 2; k++) if (a[i][j] <= a[i + 1][k]) {
int u = dp[i + 1][k].fi;
int v = dp[i + 1][k].se;
if (k == 0) {
l++;
r++;
}
if (u < 0) {
dp[i + 1][k] = mp(l, r);
} else {
dp[i + 1][k] = mp(min(l, u), max(r, v));
}
if (k == 0) {
l--;
r--;
}
}
}
ans = "-1";
for (int i = 0; i < 2; i++) {
if (dp[2 * n][i].fi <= n && n <= dp[2 * n][i].se) {
ans.clear();
trace(2 * n, i, n);
break;
}
}
cout << ans;
return 0;
}
