#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;
#define F0R(i, a) for(int i=0; i<a; i++)
#define FOR(i, a, b) for(int i=a; i<=b; i++)
#define RFOR(i, b, a) for(int i=b; i>=a; i--)
#define f first
#define s second
#define pb push_back
#define INF 0x3f3f3f3f
#define MOD 998244353LL
#define MN 1000005
int n;
int a[MN], b[MN];
pii rg[MN][2]; //# A chosen, min-max
int main(){
cin >> n;
FOR(i, 1, 2*n) cin >> a[i];
FOR(i, 1, 2*n) cin >> b[i];
FOR(i, 1, 2*n) rg[i][0] = rg[i][1] = {INF, -INF};
FOR(i, 1, 2*n){
if(a[i] >= a[i-1]){
rg[i][0].f = min(rg[i][0].f, rg[i-1][0].f+1);
rg[i][0].s = max(rg[i][0].s, rg[i-1][0].s+1);
}
if(a[i] >= b[i-1]){
rg[i][0].f = min(rg[i][0].f, rg[i-1][1].f+1);
rg[i][0].s = max(rg[i][0].s, rg[i-1][1].s+1);
}
if(b[i] >= a[i-1]){
rg[i][1].f = min(rg[i][1].f, rg[i-1][0].f);
rg[i][1].s = max(rg[i][1].s, rg[i-1][0].s);
}
if(b[i] >= b[i-1]){
rg[i][1].f = min(rg[i][1].f, rg[i-1][1].f);
rg[i][1].s = max(rg[i][1].s, rg[i-1][1].s);
}
}
int onA, cur=n;
if(rg[2*n][0].f <= n && rg[2*n][0].s >= n){
onA = true;
} else if(rg[2*n][1].f <= n && rg[2*n][1].s >= n){
onA = false;
} else{
cout << "-1\n";
return 0;
}
string s;
RFOR(i, 2*n, 1){
if(onA) s.pb('A');
else s.pb('B');
if(onA){
--cur;
if(a[i-1] <= a[i] && rg[i-1][0].f <= cur && cur <= rg[i-1][0].s){
onA = true;
} else if(b[i-1] <= a[i] && rg[i-1][1].f <= cur && cur <= rg[i-1][1].s){
onA = false;
} else{
assert(false);
}
} else{
if(a[i-1] <= b[i] && rg[i-1][0].f <= cur && cur <= rg[i-1][0].s){
onA = true;
} else if(b[i-1] <= b[i] && rg[i-1][1].f <= cur && cur <= rg[i-1][1].s){
onA = false;
} else{
assert(false);
}
}
}
reverse(s.begin(), s.end());
cout << s << "\n";
return 0;
}
