#include <bits/stdc++.h>
#ifdef NON_SUBMIT
#define TEST(n) (n)
#define tout cerr
#else
#define TEST(n) ((void)0)
#define tout cin
#endif
using namespace std;
int A[1000001][2], L[1000001][2], R[1000001][2];
int main()
{
ios::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
TEST(freopen("input.txt","r",stdin));
TEST(freopen("output.txt","w",stdout));
TEST(freopen("debug.txt","w",stderr));
int N, v, b=0;
string ans;
cin>>N; memset(L,0x7f,sizeof(L)); memset(R,0x80,sizeof(R));
L[0][0]=L[0][1]=R[0][0]=R[0][1]=0;
for(int i=1;i<=2*N;i++) cin>>A[i][0];
for(int i=1;i<=2*N;i++) {
cin>>A[i][1];
for(int j=0;j<2;j++) if(L[i-1][j]<=R[i-1][j]) for(int k=0;k<2;k++) if(A[i-1][j]<=A[i][k]) {
L[i][k]=min(L[i][k],L[i-1][j]+(k ? 1:-1));
R[i][k]=max(R[i][k],R[i-1][j]+(k ? 1:-1));
}
}
if(L[2*N][0]<=0 && 0<=R[2*N][0]) v=0;
else if(L[2*N][1]<=0 && 0<=R[2*N][1]) v=1;
else {
cout<<"-1\n";
return 0;
}
for(int i=2*N;--i;) {
ans.push_back('A'+v);
b-=v ? 1:-1;
for(int j=0;j<2;j++) if(A[i][j]<=A[i+1][v] && L[i][j]<=b && b<=R[i][j]) {
v=j;
break;
}
}
ans.push_back('A'+v);
reverse(ans.begin(),ans.end());
cout<<ans<<'\n';
return 0;
}
