#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define se second
#define fi first
#define ll long long
#define ii pair<ll, ll>
const long mxN = 5e5 + 7, inf = 1e9 + 7;
bool id[mxN];
int n, a[mxN][3], mx[mxN], mn[mxN], ans[mxN];
vector<ii> v;
int cvert(bool j)
{
if (j == 1)
return 1;
return -1;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
cin >> n;
n *= 2;
for (int i = 0; i <= 1; i++)
{
for (int j = 1; j <= n; j++)
{
cin >> a[j][i];
ans[j] = -1;
id[j] = a[j][1] >= a[j][0];
}
}
a[n + 1][0] = a[n + 1][1] = inf;
int sum = 0;
for (int i = n - 1; i > 0; i--)
{
if (a[i][id[i]] > a[i + 1][id[i + 1]])
{
id[i] = ans[i] = id[i] ^ 1;
sum += cvert(ans[i]);
}
}
int l = 1;
for (int i = 1; i <= n; i++)
{
if (min(a[i][0], a[i][1]) > max(a[i][0], a[i][1]))
{
cout << -1;
return 0;
}
if (ans[i] != -1)
{
if (l < i)
v.push_back({l, i - 1});
l = i + 1;
}
if (a[i][id[i]] <= min(a[i + 1][0], a[i + 1][1]))
{
if (l <= i)
v.push_back({l, i});
l = i + 1;
}
}
for (int j = 1; j <= v.size(); j++)
{
int cur = 0;
for (int i = v[j - 1].fi; i <= v[j - 1].se; i++)
cur -= cvert(id[i]);
mn[j] = mx[j] = cur;
for (int i = v[j - 1].fi; i <= v[j - 1].se; i++)
{
id[i] ^= 1;
if (a[i - 1][id[i - 1]] > a[i][id[i]])
break;
cur -= 2 * cvert(id[i]);
mn[j] = min(mn[j], cur);
mx[j] = max(mx[j], cur);
}
mn[j] += mn[j - 1];
mx[j] += mx[j - 1];
}
if (sum < mn[v.size()] || mx[v.size()] < sum)
{
cout << -1;
return 0;
}
for (int j = v.size() - 1; j >= 0; j--)
{
for (int i = v[j].fi; i <= v[j].se; i++)
{
ans[i] = a[i][1] >= a[i][0];
sum += cvert(ans[i]);
}
for (int i = v[j].fi; i <= v[j].se; i++)
{
if (mn[j] <= sum && sum <= mx[j])
break;
ans[i] ^= 1;
sum += 2 * cvert(ans[i]);
}
}
for (int i = 1; i <= n; i++)
cout << char('A' + ans[i]);
}
