// So that's how you want it, womanizer?!
// That's rude. It's pure love.
// Then I fight for justice!
#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n; cin >> n, n *= 2; string odp;
int a[n+1], b[n+1], dp[n+1][3][2];
dp[0][2][0] = dp[0][2][1] = a[0] = b[0] = 0;
bool czy[n+1][2];
for (int i = 1; i <= n; i++)
cin >> a[i], odp += 'x', czy[i][0] = czy[i][1] = false;
for (int i = 1; i <= n; i++) {
cin >> b[i];
if (a[i] >= max(a[i-1],b[i-1]))
dp[i][0][0] = dp[i-1][2][0]+1, dp[i][0][1] = dp[i-1][2][1]+1;
else if (a[i] >= a[i-1])
czy[i][0] = czy[i-1][0], dp[i][0][0] = dp[i-1][0][0]+1, dp[i][0][1] = dp[i-1][0][1]+1;
else if (a[i] >= b[i-1])
czy[i][0] = czy[i-1][1], dp[i][0][0] = dp[i-1][1][0]+1, dp[i][0][1] = dp[i-1][1][1]+1;
else
czy[i][0] = true;
if (b[i] >= max(a[i-1],b[i-1]))
dp[i][1][0] = dp[i-1][2][0]-1, dp[i][1][1] = dp[i-1][2][1]-1;
else if (b[i] >= a[i-1])
czy[i][1] = czy[i-1][0], dp[i][1][0] = dp[i-1][0][0]-1, dp[i][1][1] = dp[i-1][0][1]-1;
else if (b[i] >= b[i-1])
czy[i][1] = czy[i-1][1], dp[i][1][0] = dp[i-1][1][0]-1, dp[i][1][1] = dp[i-1][1][1]-1;
else
czy[i][1] = true;
if (czy[i][0] && czy[i][1]) {
cout << -1 << endl;
return 0;
}
if (czy[i][0] && !czy[i][1])
dp[i][2][0] = dp[i][1][0], dp[i][2][1] = dp[i][1][1];
else if (!czy[i][0] && czy[i][1])
dp[i][2][0] = dp[i][0][0], dp[i][2][1] = dp[i][0][1];
else
dp[i][2][0] = min(dp[i][0][0],dp[i][1][0]), dp[i][2][1] = max(dp[i][0][1],dp[i][1][1]);
//cerr << dp[i][0][0] << " " << dp[i][0][1] << " " << dp[i][1][0] << " " << dp[i][1][1] << " " << dp[i][2][0] << " " << dp[i][2][1] << endl;
}
int j = -1, v = 0;
if (!czy[n][0] && dp[n][0][0] <= v && dp[n][0][1] >= v)
j = 0, odp[n-1] = 'A';
else if (!czy[n][1] && dp[n][1][0] <= v && dp[n][1][1] >= v)
j = 1, odp[n-1] = 'B';
if (j == -1)
cout << -1 << endl;
else {
for (int i = n-1; i > 0; i--) {
if (j == 0) {
v--;
if (!czy[i][0] && a[i] <= a[i+1] && dp[i][0][0] <= v && dp[i][0][1] >= v)
odp[i-1] = 'A';
else
odp[i-1] = 'B', j = 1;
}
else {
v++;
if (!czy[i][0] && a[i] <= b[i+1] && dp[i][0][0] <= v && dp[i][0][1] >= v)
odp[i-1] = 'A', j = 0;
else
odp[i-1] = 'B';
}
}
cout << odp << endl;
}
return 0;
}
/*
zbiór możliwych bilansów zawsze tworzy przedział
A B A+B
[0,0]
[1,1] [-1,-1] [-1,1]
[2,2] [-2,0] [-2,2]
x [1,1] [1,1]
[2,2] [0,0] [0,2]
[1,3] [-1,1] [-1,3]
x [-2,0] [-2,0]
*/
