#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
#define all(x) x.begin(), x.end()
#define ms(x, a) memset(x, a, sizeof(x))
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values){
cout << vars << " = ";
string delim = "";
(...,(cout << delim << values, delim = ", "));
cout << endl;
}
//===========================================
const int MAX = 1e6+5;
int a[MAX], b[MAX], dp[2][2][MAX];
int main(){
cin.tie(0)->sync_with_stdio(0);
int n; cin >> n; n*=2;
for (int i = 1; i <= n; i++) cin >> a[i];
for (int i = 1; i <= n; i++) cin >> b[i];
for (int i = 1; i <= n; i++){
dp[0][0][i] = dp[1][0][i] = INF;
if (a[i] >= a[i-1]){
dp[0][0][i] = min(dp[0][0][i], dp[0][0][i-1]+1);
dp[0][1][i] = max(dp[0][1][i], dp[0][1][i-1]+1);
}
if (a[i] >= b[i-1]){
dp[0][0][i] = min(dp[0][0][i], dp[1][0][i-1]+1);
dp[0][1][i] = max(dp[0][1][i], dp[1][1][i-1]+1);
}
if (b[i] >= a[i-1]){
dp[1][0][i] = min(dp[1][0][i], dp[0][0][i-1]);
dp[1][1][i] = max(dp[1][1][i], dp[0][1][i-1]);
}
if (b[i] >= b[i-1]){
dp[1][0][i] = min(dp[1][0][i], dp[1][0][i-1]);
dp[1][1][i] = max(dp[1][1][i], dp[1][1][i-1]);
}
}
//deb(dp[0][0][n], dp[1][0][n], dp[0][1][n], dp[1][1][n]);
if ((dp[0][0][n] <= n/2 && n/2 <= dp[0][1][n]) ||
(dp[1][0][n] <= n/2 && n/2 <= dp[1][1][n])){
string res = "";
int c = (dp[1][0][n] <= n/2 && n/2 <= dp[1][1][n]);
int rem = n/2;
for (int i = n; i; i--){
res += (c? 'B' : 'A');
rem -= (!c);
if (!c){
if (a[i] >= a[i-1] && dp[0][0][i-1] <= rem && rem <= dp[0][1][i-1]){
c = 0;
} else c = 1;
} else {
if (b[i] >= a[i-1] && dp[0][0][i-1] <= rem && rem <= dp[0][1][i-1]){
c = 0;
} else c = 1;
}
}
assert(!rem);
reverse(all(res));
int curr = 0;
for (int i = 1; i <= n; i++){
int x = (res[i-1] == 'A'? a[i] : b[i]);
assert(x >= curr);
curr = x;
}
cout << res << "\n";
return 0;
}
cout << -1 << "\n";
}
