//joisc怎麼也有水題阿，雖然我不會，但有猜到梗
#include <bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define fs first
#define sc second
int n, a[1110000], b[1110000];
pii dp[1110000][2];
pii dead = {10000000, -10000000};
int main () {
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n;
for (int i = 1; i <= n * 2; i++) cin >> a[i];
for (int i = 1; i <= n * 2; i++) cin >> b[i];
a[0] = b[0] = -1, dp[0][0] = dp[0][1] = {0, 0};
for (int i = 1; i <= n * 2; i++) dp[i][0] = dp[i][1] = dead;
for (int i = 1; i <= n * 2; i++) {
{
bool y0 = (a[i] >= a[i - 1]) and (dp[i - 1][0] != dead), y1 = (a[i] >= b[i-1]) and (dp[i - 1][1] != dead);
if (y0 and y1) {
dp[i][0] . fs = min(dp[i - 1][0].fs, dp[i - 1][1].fs) + 1;
dp[i][0] . sc = max(dp[i - 1][0].sc, dp[i - 1][1].sc) + 1;
}
else if (y0) dp[i][0] = {dp[i - 1][0].fs + 1, dp[i - 1][0].sc + 1};
else if (y1) dp[i][0] = {dp[i - 1][1].fs + 1, dp[i - 1][1].sc + 1};
}
{
bool y0 = (b[i] >= a[i - 1]) and (dp[i - 1][0] != dead), y1 = (b[i] >= b[i-1]) and (dp[i - 1][1] != dead);
if (y0 and y1) {
dp[i][1] . fs = min(dp[i - 1][0].fs, dp[i - 1][1].fs);
dp[i][1] . sc = max(dp[i - 1][0].sc, dp[i - 1][1].sc);
}
else if (y0) dp[i][1] = dp[i - 1][0];
else if (y1) dp[i][1] = dp[i - 1][1];
}
}
int now = 2;
if (dp[n * 2][0] != dead and dp[n * 2][0].fs <= n and dp[n * 2][0].sc >= n) now = 0;
if (dp[n * 2][1] != dead and dp[n * 2][1].fs <= n and dp[n * 2][1].sc >= n) now = 1;
if (now == 2) {
cout << "-1\n";
return 0;
}
string ans;
int used = 0;
for (int i = n * 2; i >= 1; i--) {
int me = a[i];
if (now == 1) ans += "B", me = b[i];
else ans += "A", used++;
if (dp[i - 1][1] != dead and dp[i - 1][1].fs + used <= n and dp[i - 1][1].sc + used >= n and b[i -1] <= me) now = 1;
else now = 0;
}
reverse(ans.begin(), ans.end());
cout << ans << '\n';
return 0;}
