#include <bits/stdc++.h>
#define ST first
#define ND second
#define PB push_back
#define _ ios_base::sync_with_stdio(0); cin.tie(0);
using namespace std;
using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
const int nax = 1000*1000+10,INF=1e9+10;
int n;
int a[nax], b[nax];
pi dp[nax][2];
int main() {_
cin >> n;
for(int i=1; i<=2*n; i++) cin >> a[i];
for(int i=1; i<=2*n; i++) cin >> b[i];
dp[0][1] = dp[0][0] = {0,0};
for(int i=1; i<=2*n; i++) {
dp[i][0] = dp[i][1] = {INF,-INF};
if(a[i]>=a[i-1]) {
dp[i][0] = {min(dp[i][0].ST,dp[i-1][0].ST+1),max(dp[i][0].ND,dp[i-1][0].ND+1)};
}
if(a[i]>=b[i-1]) {
dp[i][0] = {min(dp[i][0].ST,dp[i-1][1].ST+1),max(dp[i][0].ND,dp[i-1][1].ND+1)};
}
if(b[i]>=b[i-1]) {
dp[i][1] = {min(dp[i][1].ST,dp[i-1][1].ST),max(dp[i][1].ND,dp[i-1][1].ND)};
}
if(b[i]>=a[i-1]) {
dp[i][1] = {min(dp[i][1].ST,dp[i-1][0].ST),max(dp[i][1].ND,dp[i-1][0].ND)};
}
}
int x = 2*n, y = n, last = INF;
bool ok = 1;
string ans = "";
while(x>0) {
if(dp[x][0].ST<=y&&y<=dp[x][0].ND&&a[x]<=last) {
last = a[x];
x--;
y--;
ans+="A";
} else if(dp[x][1].ST<=y&&y<=dp[x][1].ND&&b[x]<=last) {
last = b[x];
x--;
ans+="B";
} else {
ok = 0;
break;
}
}
if(!ok) {
cout<<"-1";
return 0;
}
reverse(ans.begin(),ans.end());
cout<<ans;
}
