#include <bits/stdc++.h>
#define N 1000005
using namespace std;
int A[N], B[N], LIS[N], n, minv[N], maxv[N], bt[N];
string ans;
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
n <<= 1;
priority_queue<array<int,2>> miv, mav;
for(int i = 1; i <= n; i ++) {
cin >> A[i];
}
for(int i = 1; i <= n; i ++) {
cin >> B[i];
}
for(int i = 1; i <= n;) {
int j = i+1;
while(j <= n && B[j] >= B[j-1]) j ++;
for(int k = i; k < j; k ++) {
LIS[k] = j-1;
}
i = j;
}
for(int i = 1; i <= n; i ++) {
while(miv.size() && LIS[miv.top()[1]+1] != LIS[i-1]) miv.pop();
while(mav.size() && LIS[mav.top()[1]+1] != LIS[i-1]) mav.pop();
if(A[i-1] <= A[i]) {
minv[i] = minv[i-1]+1;
maxv[i] = maxv[i-1]+1;
bt[i] = i-1;
} else {
minv[i] = N;
maxv[i] = -N;
}
if(miv.size() && B[i-1] <= A[i]) minv[i] = min(minv[i], 1-miv.top()[0]);
if(mav.size() && B[i-1] <= A[i]) {
maxv[i] = max(maxv[i], mav.top()[0]+1);
if(maxv[i] == mav.top()[0]+1) {
bt[i] = mav.top()[1];
}
}
if(B[i] >= A[i-1]) {
miv.push({-minv[i-1],i-1});
mav.push({maxv[i-1], i-1});
}
}
ans.resize(n);
bool okb = 1;
for(int i = n; i >= 1; i --) {
if(okb && maxv[i] == n/2 && (i == n || A[i] <= B[i+1])) {
int c = i;
while(c) {
ans[c-1] = 'A';
c = bt[c];
}
for(int j = 0; j < n; j ++) {
if(ans[j] == 'A') cout << 'A';
else cout << 'B';
}
return 0;
}
if(i != n && B[i] > B[i+1]) okb = 0;
}
cout << -1;
}
