#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MAX = 1e6 + 5;
const int inf = 1e9;
int N, a[MAX], b[MAX], result[MAX];
pair<int, int> dp[MAX][2]; //nA - nB
void update(pair<int, int>& a, const pair<int, int>& b, int v){
a.first = min(a.first, b.first + v);
a.second = max(a.second, b.second + v);
}
int eval(int i, int lst){
return (lst ? b[i] : a[i]);
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
freopen("task.inp", "r", stdin);
freopen("task.out", "w", stdout);
#endif // LOCAL
cin >> N;
for(int i = 1; i <= 2 * N; ++i) cin >> a[i];
for(int i = 1; i <= 2 * N; ++i) cin >> b[i];
dp[1][0] = {1, 1};
dp[1][1] = {-1, -1};
for(int i = 2; i <= 2 * N; ++i){
dp[i][0] = {inf, -inf};
dp[i][1] = {inf, -inf};
if(a[i - 1] <= a[i]) update(dp[i][0], dp[i - 1][0], +1);
if(b[i - 1] <= a[i]) update(dp[i][0], dp[i - 1][1], +1);
if(a[i - 1] <= b[i]) update(dp[i][1], dp[i - 1][0], -1);
if(b[i - 1] <= b[i]) update(dp[i][1], dp[i - 1][1], -1);
}
int target = 0, lst = 1e9;
for(int i = 2 * N; i >= 1; --i){
if(dp[i][0].first <= target && target <= dp[i][0].second && a[i] <= lst){
--target;
result[i] = 0;
lst = a[i];
} else if(dp[i][1].first <= target && target <= dp[i][1].second && b[i] <= lst){
++target;
result[i] = 1;
lst = b[i];
} else{
cout << -1 << '\n';
return 0;
}
}
assert(target == 0);
for(int i = 1; i <= 2 * N; ++i) cout << (result[i] ? 'B' : 'A');
return 0;
}
