#pragma GCC optimize("O2")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,sse,sse2,ssse3,tune=native")
#include<bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
using namespace std;
using ll = long long;
using vi = vector<ll>;
using pi = pair<ll, ll>;
using vpi = vector<pi>;
const int maxn = 1005000 + 22, mod = 998244353;
int n, a[maxn], b[maxn], mn[maxn][2], mx[maxn][2];
string ans;
bool bt(int v, int l, int bl = n/2, int lst = 2e9) {
if(bl<0||v<bl||(v && (l?b:a)[v-1]>lst)) return false;
if(bl>mx[v][l]||bl<mn[v][l]) return false;
if(!v) return true;
if(!bt(v-1, 0, bl - (l==1), (l?b:a)[v-1])&&!bt(v-1, 1, bl - (l==1), (l?b:a)[v-1])) return 0;
//cout << v << " " << l << " " << bl << '\n';
ans += "AB"[l];
return true;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n;
n *= 2;
for(int i = 0; i < n; i++) cin >> a[i];
for(int i = 0; i < n; i++) cin >> b[i];
memset(mn, 0x3f, sizeof mn);
memset(mx, -0x3f, sizeof mx);
mn[0][0] = mx[0][0] = 0;
for(int i = 0; i < n; i++) {
for(int j = 0; j < 2; j++) {
int lst = (i?(j?b:a)[i-1]:0);
if(a[i]>=lst) {
mn[i+1][0] = min(mn[i+1][0], mn[i][j]);
mx[i+1][0] = max(mx[i+1][0], mx[i][j]);
}
if(b[i]>=lst) {
mn[i+1][1] = min(mn[i+1][1], mn[i][j]+1);
mx[i+1][1] = max(mx[i+1][1], mx[i][j]+1);
}
}
}
if(!bt(n, 0)&&!bt(n, 1)) cout << -1;
cout << ans << '\n';
}
