#include<bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 1e6 + 6;
int a[maxn][2], dpmx[maxn][2], dpmi[maxn][2], w[2];
void solve() {
int n; cin >> n;
n *= 2;
for(int i = 1; i <= n; i++) cin >> a[i][0];
for(int i = 1; i <= n; i++) cin >> a[i][1];
dpmx[1][0] = dpmi[1][0] = w[0] = 1;
dpmx[1][1] = dpmi[1][1] = w[1] = -1;
for(int i = 2; i <= n; i++){
for(int cur = 0; cur <= 1; cur++){
dpmx[i][cur] = -1e18;
dpmi[i][cur] = 1e18;
for(int pre = 0; pre <= 1; pre++){
if(a[i - 1][pre] <= a[i][cur]){
dpmx[i][cur] = max(dpmx[i][cur], dpmx[i - 1][pre] + w[cur]);
dpmi[i][cur] = min(dpmi[i][cur], dpmi[i - 1][pre] + w[cur]);
}
}
}
}
int sum = 0, pos = n, state;
if(dpmi[n][0] <= 0 && 0 <= dpmx[n][0]) state = 0;
else if(dpmi[n][1] <= 0 && 0 <= dpmx[n][1]) state = 1;
else{
cout << -1;
return;
}
vector<int> res;
while(pos >= 1){
res.push_back(state);
sum -= w[state];
pos--;
if(a[pos][0] <= a[pos + 1][state] && dpmi[pos][0] <= sum && sum <= dpmx[pos][0]) state = 0;
else if(a[pos][1] <= a[pos + 1][state] && dpmi[pos][1] <= sum && sum <= dpmx[pos][1]) state = 1;
}
reverse(res.begin(), res.end());
for(int u : res) cout << (u ? 'B' : 'A');
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
solve();
}
