#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cassert>
#include <vector>
#include <cstring>
#include <cstdlib>
using namespace std;
#define X first
#define Y second
#define mp make_pair
#define pb push_back
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <int, pii> pip;
typedef pair <pii, int> ppi;
typedef pair <ll, ll> pll;
const int INF=0x3f3f3f3f;
const int N=1e6+5;
int n;
int A[N], B[N];
pii a[N], b[N];
string sol="";
pii mrg(pii a, pii b) {
if (a.X<0) return b;
if (b.X<0) return a;
if (b.X-1 > a.Y || b.Y+1 < a.X) {
assert(0);
}
pii res=a;
if (b.X<res.X) res.X=b.X;
if (b.Y>res.Y) res.Y=b.Y;
return res;
}
void load() {
scanf("%d", &n);
for (int i=0; i<2*n; ++i) scanf("%d", A+i);
for (int i=0; i<2*n; ++i) scanf("%d", B+i);
}
void solve() {
a[0]=mp(1, 1); b[0]=mp(0, 0);
// printf("i==%d: [%d, %d], [%d, %d]\n", 0, 1, 1, 0, 0);
for (int i=1; i<2*n; ++i) {
a[i]=mp(-INF, -INF);
b[i]=mp(-INF, -INF);
if (B[i]>=B[i-1]) b[i]=mrg(b[i], b[i-1]);
if (B[i]>=A[i-1]) b[i]=mrg(b[i], a[i-1]);
if (A[i]>=A[i-1]) a[i]=mrg(a[i], mp(a[i-1].X+1, a[i-1].Y+1));
if (A[i]>=B[i-1]) a[i]=mrg(a[i], mp(b[i-1].X+1, b[i-1].Y+1));
// printf("i==%d: [%d, %d], [%d, %d]\n", i, a[i].X, a[i].Y, b[i].X, b[i].Y);
}
int mogua=0, mogub=0, cnt=n;
if (a[2*n-1].X<=n && a[2*n-1].Y>=n) mogua=1;
else if (b[2*n-1].X<=n && b[2*n-1].Y>=n) mogub=1;
else {
printf("-1\n");
return;
}
for (int i=2*n-1; i>=0; --i) {
if (mogua) {
sol+='A';
cnt--;
mogua=0;
mogub=0;
if (!i) break;
if (a[i-1].X<=cnt && a[i-1].Y>=cnt && A[i-1]<=A[i]) mogua=1;
else mogub=1;
}
else {
sol+='B';
mogua=0;
mogub=0;
if (!i) break;
if (a[i-1].X<=cnt && a[i-1].Y>=cnt && A[i-1]<=B[i]) mogua=1;
else mogub=1;
}
}
reverse(sol.begin(), sol.end());
printf("%s\n", sol.c_str());
}
int main() {
load();
solve();
return 0;
}
