#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const ll inf = 1e18;
const int N = 1e5 + 5;
signed main() {
int n; cin >> n;
vector<array<int, 2> > a(2*n+1);
for(int i=1; i<=2*n; i++) cin >> a[i][0];
for(int i=1; i<=2*n; i++) cin >> a[i][1];
vector<vector<int> > dpL(2*n+1, vector<int>(2, 1e9));
vector<vector<int> > dpR(2*n+1, vector<int>(2, -1e9));
dpL[1] = { 0, 1 };
dpR[1] = { 0, 1 };
for(int i=2; i<=2*n; i++) {
for(int j=0; j<2; j++) {
for(int k=0; k<2; k++) {
if(a[i][j] >= a[i-1][k]) {
dpL[i][j] = min(dpL[i][j], dpL[i-1][k] + j);
dpR[i][j] = max(dpR[i][j], dpR[i-1][k] + j);
}
}
}
}
int p=-1;
for(int i=0; i<2; i++)
if(dpL[2*n][i] <= n && n <= dpR[2*n][i]) p = i;
if(p == -1) {
cout << -1 << endl;
return 0;
}
string ans(2*n+1, 'A');
if(p) ans[2*n] = 'B';
int l=n-p, pos=2*n-1, last = a[2*n][p];
for(; pos; pos--) {
if(dpL[pos][0] <= l && l <= dpR[pos][0] && a[pos][0] <= last) {
last = a[pos][0];
} else if(dpL[pos][1] <= l && l <= dpR[pos][1] && a[pos][1] <= last) {
ans[pos]++;
last = a[pos][1];
l--;
} else {
cout << -1 << endl;
return 0;
}
}
for(int i=1; i<=2*n; i++) cout << ans[i];
}
