//~ while (clock()<=69*CLOCKS_PER_SEC)
//~ #pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("O3")
//~ #pragma GCC target ("avx2")
//~ #pragma GCC optimize("Ofast")
//~ #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//~ #pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
template <typename T>
using ordered_set =
tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
*this << "[";
for (auto it = d.b; it != d.e; ++it)
*this << ", " + 2 * (it == d.b) << *it;
ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define shandom_ruffle random_shuffle
using ll=long long;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using vi=vector<int>;
using vll=vector<ll>;
const int nax=1000*1007;
int n;
int tab[nax][2];
int dpl[nax][2];
int dpr[nax][2];
char ans[nax];
void no()
{
printf("-1");
exit(0);
}
void check()
{
int pre=0;
for (int i=1; i<=n; i++)
{
int wzn=1e9+5;
for (int j=0; j<2; j++)
if (tab[i][j]>=pre)
wzn=min(wzn, tab[i][j]);
if (wzn>1e9)
no();
pre=wzn;
}
}
void rec(int i, int sl, int jos)
{
ans[i]='A'+sl;
jos-=(sl==1);
if (i==1)
{
assert(jos==0);
return;
}
for (int j=0; j<2; j++)
if (tab[i][sl]>=tab[i-1][j] && dpl[i-1][j]<=jos && dpr[i-1][j]>=jos)
{
rec(i-1, j, jos);
break;
}
}
int main()
{
scanf("%d", &n);
n=2*n;
for (int i=1; i<=n; i++)
scanf("%d", &tab[i][0]);
for (int i=1; i<=n; i++)
scanf("%d", &tab[i][1]);
check();
for (int i=1; i<=n; i++)
for (int j=0; j<2; j++)
dpl[i][j]=1e9, dpr[i][j]=-1e9;
dpl[1][0]=0;
dpr[1][0]=0;
dpl[1][1]=1;
dpr[1][1]=1;
for (int i=2; i<=n; i++)
for (int x=0; x<2; x++)
for (int y=0; y<2; y++)
{
if (tab[i-1][x]>tab[i][y])
continue;
dpl[i][y]=min(dpl[i][y], dpl[i-1][x]+(y==1));
dpr[i][y]=max(dpr[i][y], dpr[i-1][x]+(y==1));
}
int ok=0;
for (int i=0; i<2; i++)
if (dpl[n][i]<=n/2 && dpr[n][i]>=n/2)
{
rec(n, i, n/2);
ok=1;
break;
}
if (ok==0)
no();
for (int i=1; i<=n; i++)
printf("%c", ans[i]);
return 0;
}
