#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
#define X first
#define Y second
#define lc id<<1
#define rc lc|1
#define mid ((l+r)>>1)
#define all(x) x.begin(), x.end()
#define SZ(x) int(x.size())
const int MXN = 5e5+5;
int n, a[MXN], b[MXN];
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
cin >> n;
for(int i=1; i<=2*n; i++) cin >> a[i];
for(int i=1; i<=2*n; i++) cin >> b[i];
int res=0;
string ans=0;
for(int i=1; i<=n; i++)
if(a[i]>=res) {
if(b[i]>=res) {
if(a[i]<=b[i]) {
res = a[i];
ans.push_back('A');
}
else {
res = b[i];
ans.push_back('B');
}
}
else
res = a[i],
ans.push_back('A');
}
else if(b[i]>=res)
res = b[i],
ans.push_back('B');
else {
cout << "-1\n";
return 0;
}
cout << ans << '\n';
return 0;
}
