#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define X first
#define Y second
#define y0 y12
#define y1 y22
#define INF 987654321
#define PI 3.141592653589793238462643383279502884
#define fup(i,a,b,c) for(int (i)=(a);(i)<=(b);(i)+=(c))
#define fdn(i,a,b,c) for(int (i)=(a);(i)>=(b);(i)-=(c))
#define MEM0(a) memset((a),0,sizeof(a))
#define MEM_1(a) memset((a),-1,sizeof(a))
#define ALL(a) a.begin(),a.end()
#define COMPRESS(a) sort(ALL(a));a.resize(unique(ALL(a))-a.begin())
#define SYNC ios_base::sync_with_stdio(false);cin.tie(0)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef double db;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int, int> Pi;
typedef pair<ll, ll> Pll;
typedef pair<ld, ld> Pd;
typedef vector<int> Vi;
typedef vector<ll> Vll;
typedef vector<ld> Vd;
typedef vector<Pi> VPi;
typedef vector<Pll> VPll;
typedef vector<Pd> VPd;
typedef tuple<int, int, int> iii;
typedef tuple<int, int, int, int> iiii;
typedef tuple<ll, ll, ll> LLL;
typedef vector<iii> Viii;
typedef vector<LLL> VLLL;
typedef complex<double> base;
const int MOD = 1000000021;
ll POW(ll a, ll b, ll MMM = MOD) { ll ret = 1; for (; b; b >>= 1, a = (a*a) % MMM)if (b & 1)ret = (ret*a) % MMM; return ret; }
int dx[] = { 0,1,0,-1,1,1,-1,-1 }, dy[] = { 1,0,-1,0,1,-1,1,-1 };
int ddx[] = { -1,-2,1,-2,2,-1,2,1 }, ddy[] = { -2,-1,-2,1,-1,2,1,2 };
int a[2][1000005];
int d1[2][1000005],d2[2][1000005];
int n;
int go1(int k,int N){
if(N==2*n)return 0;
int &ret=d1[k][N];
if(~ret)return ret;
ret=-INF;
if(a[k][N]<=a[0][N+1])ret=max(ret,1+go1(0,N+1));
if(a[k][N]<=a[1][N+1])ret=max(ret,go1(1,N+1));
return ret;
}
int go2(int k,int N){
if(N==2*n)return 0;
int &ret=d2[k][N];
if(~ret)return ret;
ret=-INF;
if(a[k][N]<=a[0][N+1])ret=max(ret,go2(0,N+1));
if(a[k][N]<=a[1][N+1])ret=max(ret,1+go2(1,N+1));
return ret;
}
vector<char> ans;
void track(int k,int N,int remA,int remB){
if(N==2*n)return;
if(a[k][N]<=a[0][N+1]){
if(remA-1<=go1(0,N+1) && remB<=go2(0,N+1)){
ans.pb('A');
track(0,N+1,remA-1,remB);
return;
}
}
if(a[k][N]<=a[1][N+1]){
if(remA<=go1(1,N+1) && remB-1<=go2(1,N+1)){
ans.pb('B');
track(1,N+1,remA,remB-1);
return;
}
}
}
int main(){
MEM_1(d1);MEM_1(d2);
scanf("%d",&n);
fup(i,1,2*n,1)scanf("%d",&a[0][i]);
fup(i,1,2*n,1)scanf("%d",&a[1][i]);
//if(go1(0,0)<n || go2(0,0)<n)return !printf("-1\n");
track(0,0,n,n);
if(ans.size()!=2*n)return !printf("-1\n");
for(char c:ans)printf("%c",c);
}
