#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3,unroll-loops")
using namespace std;
#define int long long
#define pii pair<int,int>
#define ff first
#define ss second
#define sp << " " <<
#define all(cont) cont.begin(),cont.end()
#define vi vector<int>
const int inf = 1e17,N = 2e6+1,MOD = (1LL<<61)-1,B = 23;
void solve() {
int n;
cin >> n;
n*=2;
int v[n+1][2]{};
for (int i=1;i<=n;i++) cin >> v[i][0];
for (int i=1;i<=n;i++) cin >> v[i][1];
pii dp[n+1][2];
for (int i=0;i<=n;i++) for (int j = 0;j<2;j++) dp[i][j] = {inf,-inf};
dp[0][0] = dp[0][1] = {0,0};
for (int i=0;i<n;i++) {
for (int j = 0;j<2;j++) {
int prv = v[i][j];
if (v[i+1][0] >= prv) {
dp[i+1][0].ff = min(dp[i+1][0].ff,dp[i][j].ff+1);
dp[i+1][0].ss = max(dp[i+1][0].ss,dp[i][j].ss+1);
}
if (v[i+1][1] >= prv) {
dp[i+1][1].ff = min(dp[i+1][1].ff,dp[i][j].ff);
dp[i+1][1].ss = max(dp[i+1][1].ss,dp[i][j].ss);
}
}
}
string ans;
if (dp[n][0].ff <= n/2 && dp[n][0].ss >= n/2) {
int ptr = n;
int cur = 0;
int usea = 0;
while (ptr >= 1) {
if (!cur) ans+='A';
else ans+='B';
if (ptr > 1) {
if (usea+dp[ptr-1][0].ff+1 <= n/2 && usea+dp[ptr-1][0].ss+1 >= n/2 && v[ptr-1][0] <= v[ptr][cur]) {
usea++;
ptr--;
cur = 0;
continue;
}
else {
ptr--;
cur = 1;
continue;
}
}
else break;
}
reverse(all(ans));
cout << ans << '\n';
return;
}
if (dp[n][1].ff <= n/2 && dp[n][1].ss >= n/2) {
int ptr = n;
int cur = 1;
int usea = 0;
while (ptr >= 1) {
if (!cur) ans+='A';
else ans+='B';
if (ptr > 1) {
if (usea+dp[ptr-1][0].ff <= n/2 && usea+dp[ptr-1][0].ss >= n/2 && v[ptr-1][0] <= v[ptr][cur]) {
usea++;
ptr--;
cur = 0;
continue;
}
else {
ptr--;
cur = 1;
continue;
}
}
else break;
}
reverse(all(ans));
cout << ans << '\n';
return;
}
cout << -1 << '\n';
return;
}
int32_t main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#ifdef Dodi
freopen("in.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif
int t = 1;
//cin >> t;
while (t --> 0) solve();
}
