#include <bits/stdc++.h>
#pragma GCC target("sse,sse2,avx2")
#pragma GCC optimize("unroll-loops,O2")
#define rep(i,l,r) for (int i = l; i < r; i++)
#define repr(i,r,l) for (int i = r; i >= l; i--)
#define X first
#define Y second
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define endl '\n'
#define debug(x) cerr << #x << " : " << x << endl;
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pll;
constexpr int N = 4e3+10,mod = 998244353,inf = 1e9+10,sq = 700;
inline int mkay(int a,int b){
if (a+b >= mod) return a+b-mod;
if (a+b < 0) return a+b+mod;
return a+b;
}
inline int poww(int a,int k){
if (k < 0) return 0;
int z = 1;
while (k){
if (k&1) z = 1ll*z*a%mod;
a = 1ll*a*a%mod;
k /= 2;
}
return z;
}
bool dp[N][N][2];
int a[N],b[N],n;
int main(){
ios :: sync_with_stdio(0); cin.tie(0);
cin >> n;
n *= 2;
rep(i,0,n) cin >> a[i];
rep(i,0,n) cin >> b[i];
dp[n-1][1][0] = 1;
dp[n-1][0][1] = 1;
repr(i,n-2,0){
rep(j,0,n){
if (a[i+1] >= b[i]) dp[i][j][1] = dp[i+1][j][0];
if (b[i+1] >= b[i]) dp[i][j][1] |= dp[i+1][j][1];
if (j && a[i+1] >= a[i]) dp[i][j][0] = dp[i+1][j-1][0];
if (j && b[i+1] >= a[i]) dp[i][j][0] |= dp[i+1][j-1][1];
}
}
if (!(dp[0][n/2][0]|dp[0][n/2][1])){
cout << -1 << endl;
return 0;
}
int sd,cur = n/2;
if (dp[0][n/2][0]) sd = 0;
else sd = 1;
rep(i,0,n){
if (sd) cout << 'B';
else cout << 'A';
if (i+1 == n) return 0;
if (sd){
if (b[i+1] >= b[i] && dp[i+1][cur][1]){
continue;
}
sd = 0;
continue;
}
if (b[i+1] >= a[i] && dp[i+1][cur-1][1]){
sd = 1;
cur--;
continue;
}
cur--;
}
return 0;
}
