#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
using ll = long long;
#define int ll
void fail() {
cout << -1;
exit(0);
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n; cin >> n;
vector<int> a(2*n); for(int i = 0; i < 2*n; i++) cin >> a[i];
vector<int> b(2*n); for(int i = 0; i < 2*n; i++) cin >> b[i];
vector<int> mx(2*n); for(int i = 0; i < 2*n; i++) mx[i] = max(a[i],b[i]);
vector<int> mn(2*n); for(int i = 0; i < 2*n; i++) mn[i] = min(a[i],b[i]);
vector<int> mnPoss(2*n);
mnPoss[0] = mn[0];
for(int i = 1; i < 2*n; i++) {
if(mnPoss[i-1]>mx[i]) fail();
else if(mnPoss[i-1]<=mn[i]) mnPoss[i] = mn[i];
else mnPoss[i] = mx[i];
}
vector<int> mxPoss(2*n);
mxPoss[2*n-1] = mx[2*n-1];
for(int i = 2*n-2; i >= 0; i--) {
if(mxPoss[i+1]<mn[i]) fail();
else if(mxPoss[i+1]>=mx[i]) mxPoss[i] = mx[i];
else mxPoss[i] = mn[i];
}
int ac = 0;
int bc = 0;
int jc = 0;
vector<int> c(2*n);
for(int i = 0; i < 2*n; i++) {
if(mnPoss[i]>mxPoss[i]) fail();
if(mnPoss[i]<=a[i]&&a[i]<=mxPoss[i]&&mnPoss[i]<=b[i]&&b[i]<=mxPoss[i]) { jc++; c[i] = 2; }
else {
if(mnPoss[i]<=a[i]&&a[i]<=mxPoss[i]) { ac++; c[i] = 0; }
else if(mnPoss[i]<=b[i]&&b[i]<=mxPoss[i]) { bc++; c[i] = 1; }
}
}
if(ac>n||bc>n||ac+jc<n||bc+jc<n) fail();
int an = n - ac;
int bn = n - bc;
int fan = 0; int fbn = 0;
string ans; ans.reserve(2*n);
int prev = 0;
for(int i = 0; i < 2*n; i++) {
if(c[i]==0) { ans.push_back('A'); fan++; prev = a[i]; }
else if(c[i]==1) { ans.push_back('B'); fbn++; prev = b[i]; }
else {
if(an>bn&&a[i]>=prev) { ans.push_back('A'); an--; fan++; prev = a[i]; }
else { ans.push_back('B'); bn--; fbn++; prev = b[i]; }
}
}
for(int i = 0; i < 2*n-1; i++) {
if(((ans[i]=='A')?a[i]:b[i])>((ans[i+1]=='A')?a[i+1]:b[i+1])) fail();
}
if(fan==n&&fbn==n) cout << ans;
else fail();
return 0;
}
