#include<bits/stdc++.h>
using namespace std;
struct Interval{
int l, r;
Interval(){}
Interval(int l, int r) : l(l), r(r){}
Interval operator + (int x) const{
return Interval{l + x, r + x};
}
bool operator == (Interval oth) const{
return l == oth.l && r == oth.r;
}
bool contains(int val){
return l <=val && val <=r;
}
};
Interval join(Interval a, Interval b){
Interval nou;
nou.l = min(a.l, b.l);
nou.r = max(a.r, b.r);
return nou;
}
const int N = 1000005;
Interval dp[N][2];
int v[2][N];
Interval IMP(INT_MAX, -INT_MAX);
bool goback(int poz, int val, int nxt){
if(poz == 0)
return true;
if(dp[poz][0].contains(val) && v[0][poz] <= nxt){
goback(poz -1, val, v[0][poz]);
cout<<"A";
return true;
}
else if(dp[poz][1].contains(val) && v[1][poz] <= nxt){
goback(poz - 1, val -1, v[1][poz]);
cout<<"B";
return true;
}
return false;
}
int main()
{
//freopen(".in","r",stdin);
ios::sync_with_stdio(false);
cin.tie(0),cout.tie(0);
int n;
cin>>n;
for(int i = 1; i<=2*n; i++){
cin>>v[0][i];
}
for(int i = 1; i<=2*n; i++){
cin>>v[1][i];
}
for(int i = 0; i <= 2* n; i++){
dp[i][0] = dp[i][1] = IMP;
}
dp[0][0] = Interval(0, 0);
for(int i = 1; i <=2*n; i++){
for(int k = 0; k <=1; k++){
if(dp[i-1][k] == IMP)
continue;
for(int j = 0; j <=1; j++){
if(v[j][i] >= v[k][i - 1]){
if(dp[i][j] == IMP)
dp[i][j] = dp[i - 1][k] + j;
else
dp[i][j] = join(dp[i][j], dp[i - 1][k] + j);
}
}
}
}
if(goback(2*n, n, INT_MAX) == false)
cout<<"-1";
return 0;
}
