#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 1e6 + 6;
int n, a[maxn][2];
pair<int, int> f[maxn][2];
pair<int, bool> trace[maxn][3][2];
void update(pair<int, int> &cur, pair<int, int> v, int delta) {
cur.first = min(cur.first, v.first + delta);
cur.second = max(cur.second, v.second + delta);
}
void solve() {
cin >> n;
n = n + n;
for(int j = 0; j < 2; ++j) {
for(int i = 1; i <= n; ++i) {
cin >> a[i][j];
}
}
for(int i = 1; i <= n; ++i) {
for(int j = 0; j < 2; ++j) {
f[i][j] = make_pair(1e9, -1e9);
}
}
for(int i = 1; i <= n; ++i) {
for(int j = 0; j < 2; ++j) {
for(int k = 0; k < 2; ++k) {
if(a[i][j] >= a[i - 1][k]) {
update(f[i][j], f[i - 1][k], (j == 0 ? 1 : -1));
}
}
// debug(i, j, f[i][j]);
}
}
int diff = 0, cur = 1e9;
string res;
for(int i = n; i; --i) {
bool flag = 0;
for(int j = 0; j < 2; ++j) {
if(f[i][j].first <= diff and diff <= f[i][j].second) {
if(a[i][j] <= cur) {
cur = a[i][j];
diff += (j == 0 ? -1 : 1);
res += char('A' + j);
flag = 1;
break;
}
}
}
if(!flag) {
cout << -1;
return;
}
}
reverse(res.begin(), res.end());
cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
