/*
IN THE NAME OF GOD
*/
#include <bits/stdc++.h>
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef long double ld;
#define F first
#define S second
#define Mp make_pair
#define pb push_back
#define pf push_front
#define size(x) ((ll)x.size())
#define all(x) (x).begin(),(x).end()
#define kill(x) cout << x << '\n', exit(0);
#define fuck(x) cout << "(" << #x << " , " << x << ")" << endl
#define endl '\n'
const int N = 1e6+23, lg = 18;
ll Mod = 1e9+7; //998244353;
inline ll MOD(ll a, ll mod=Mod) {a%=mod; (a<0)&&(a+=mod); return a;}
inline ll poww(ll a, ll b, ll mod=Mod) {
ll ans = 1;
a=MOD(a, mod);
while (b) {
if (b & 1) ans = MOD(ans*a, mod);
b >>= 1;
a = MOD(a*a, mod);
}
return ans;
}
int n, a[N], b[N];
pii dp[2][N];
string str;
pii merge(pii v, pii u) {
return Mp(min(v.F, u.F), max(v.S, u.S));
}
void solve(int bt, int id, int cnt) {
if(id==0) return;
if(bt==1)str.pb('B');
else str.pb('A');
if(bt==0) {
if(a[id]>=a[id-1] && dp[0][id-1].F<=(n/2-cnt-1) && dp[0][id-1].S>=(n/2-cnt-1)) {
solve(0, id-1, cnt+1);
return;
}
solve(1, id-1, cnt+1);
} else {
if(b[id]>=a[id-1] && dp[0][id-1].F<=(n/2-cnt) && dp[0][id-1].S>=(n/2-cnt)) {
solve(0, id-1, cnt);
return;
}
solve(1, id-1, cnt);
}
}
int main () {
ios_base::sync_with_stdio(false), cin.tie(0);
cin>>n; n*=2;
for(int i=1; i<=n; i++) cin>>a[i];
for(int i=1; i<=n; i++) cin>>b[i];
dp[0][0] = dp[1][0] = {0, 0};
for(int i=1; i<=n; i++) {
dp[0][i] = dp[1][i] = {1e9, -1e9};
if(a[i]>=a[i-1] && a[i]>=b[i-1]) dp[0][i] = merge(dp[0][i-1], dp[1][i-1]);
else if(a[i]>=a[i-1]) dp[0][i] = dp[0][i-1];
else if(a[i]>=b[i-1]) dp[0][i] = dp[1][i-1];
dp[0][i].F++, dp[0][i].S++;
if(b[i]>=a[i-1] && b[i]>=b[i-1]) dp[1][i] = merge(dp[0][i-1], dp[1][i-1]);
else if(b[i]>=a[i-1]) dp[1][i] = dp[0][i-1];
else if(b[i]>=b[i-1]) dp[1][i] = dp[1][i-1];
}
if(dp[0][n].F<=n/2 && dp[0][n].S>=n/2) {
solve(0, n, 0);
} else if(dp[1][n].F<=n/2 && dp[1][n].S>=n/2) {
solve(1, n, 0);
} else {
kill(-1);
}
reverse(all(str));
cout<<str<<endl;
return 0;
}
