#include <iostream>
#include <vector>
#include <algorithm>
#include <cassert>
using namespace std;
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) < (b)) ? (b) : (a))
using ll = long long;
int const nmax = 1000000;
struct Info{
int x;
int y;
Info operator + (Info const &a) const {
if(x == -nmax)
return a;
else if(a.x == -nmax)
return {x, y};
assert(!(min(a.y, y) + 1 < max(x, a.x)));
return {min(a.x, x), max(y, a.y)};
}
Info operator + (int const &a) const {
return {x + a, y + a};
}
bool inside(int val){
return x <= val && val <= y;
}
};
Info dp[1 + nmax][2];
int a[1 + nmax], b[1 + nmax];
Info extract(int pos, int val){
if(a[pos] <= val && b[pos] <= val)
return dp[pos][0] + dp[pos][1];
else if(a[pos] <= val) {
return dp[pos][0];
} else if(b[pos] <= val) {
return dp[pos][1];
} else
return {-nmax, -nmax};
}
void solve(int pos, int k, int val, char ch){
if(0 == pos)
return ;
if(dp[pos - 1][0].inside(k) && a[pos - 1] <= val)
solve(pos - 1, k - 1, a[pos - 1], 'A');
else if(dp[pos - 1][1].inside(k) && b[pos - 1] <= val)
solve(pos - 1, k, b[pos - 1], 'B');
else{
cout << "Wrong";
assert(1 < 0);
}
cout << ch;
}
int main()
{
int n;
cin >> n;
for(int i = 1;i <= 2 * n; i++)
cin >> a[i];
for(int i = 1;i <= 2 * n; i++)
cin >> b[i];
Info sum = ((Info){0, 0}) + ((Info){1, 1});
//*
for(int i = 1;i <= 2 * n; i++){
dp[i][0] = extract(i - 1, a[i]);
if(dp[i][0].x != -nmax)
dp[i][0] = dp[i][0] + 1;
dp[i][1] = extract(i - 1, b[i]);
}
if(dp[2 * n][0].inside(n))
solve(2 * n, n - 1, a[2 * n], 'A');
else if(dp[2 * n][1].inside(n))
solve(2 * n, n, b[2 * n], 'B');
else
cout << -1;
//*/
return 0;
}
/*
BABBABAABABA
*/
