#include <bits/stdc++.h>
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
*/
using namespace std;
// using namespace __gnu_pbds;
using namespace chrono;
// mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());
/*
template <class T> using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;
*/
//***************** CONSTANTS *****************
const int MXN = 500'000;
//***************** GLOBAL VARIABLES *****************
int A[2][2*MXN + 1], l[2][2*MXN + 1], r[2][2*MXN + 1];
//***************** AUXILIARY STRUCTS *****************
inline int readInt() {
int x = 0;
char ch = getchar_unlocked();
while (ch < '0' || ch > '9') ch = getchar_unlocked();
while (ch >= '0' && ch <= '9'){
x = (x << 3) + (x << 1) + ch - '0';
ch = getchar_unlocked();
}
return x;
}
//***************** MAIN BODY *****************
void solve(){
int N = readInt();
for(int j = 1; j >= 0; --j){
for(int i = 1; i <= 2*N; i++) A[j][i] = readInt();
}
for(int i = 1; i <= 2*N; i++){
for(int j = 0; j < 2; j++){
l[j][i] = 2*N + 1, r[j][i] = -1;
for(int k = 0; k < 2; k++)
if(A[j][i] >= A[k][i-1]){
l[j][i] = min(l[j][i], l[k][i-1] + j);
r[j][i] = max(r[j][i], r[k][i-1] + j);
}
}
}
int j = -1;
for(int k = 0; k < 2; k++)
if(l[k][2*N] <= N && r[k][2*N] >= N){
j = k;
}
if(j < 0){
cout << "-1\n";
return;
}
string ans(2*N, ' ');
int cnt = N;
for(int i = 2*N; i >= 1; --i){
ans[i - 1] = 'B' - j;
cnt -= j;
j = (A[j][i] >= A[1][i-1] && l[1][i-1] <= cnt && r[1][i-1] >= cnt);
}
cout << ans << '\n';
}
//***************** *****************
int32_t main(){
// ios_base::sync_with_stdio(NULL);
// cin.tie(NULL);
#ifdef LOCAL
auto begin = high_resolution_clock::now();
#endif
int tc = 1;
// cin >> tc;
for (int t = 0; t < tc; t++)
solve();
#ifdef LOCAL
auto end = high_resolution_clock::now();
cout << fixed << setprecision(4);
cout << "Execution Time: " << duration_cast<duration<double>>(end - begin).count() << "seconds" << endl;
#endif
return 0;
}
/*
If code gives a WA, check for the following :
1. I/O format
2. Are you clearing all global variables in between tests if multitests are a thing
3. Can you definitively prove the logic
4. If the code gives an inexplicable TLE, and you are sure you have the best possible complexity,
use faster io
*/
