#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
#include <tuple>
#include <bitset>

#define rep(i,n) for(i=0; i<n; ++i)
#define in(a) cin >> a
#define out(a,b) cout << a << b
using namespace std;
using lint = long long;

int main(void){
    lint i, j;
    lint n, m;
    in(n);
    in(m);
    vector<lint> a(n); vector<lint> b(n); vector<lint> c(n);
    rep(i,n)    in(a[i]);
    rep(i,n)    in(b[i]);
    rep(i,n)    c[i]=a[i]-b[i];
    vector<lint> d=c;
    sort(c.begin(), c.end());
    lint elem=c[n-m];
    int cnt=0;
    while(elem==c[n-m+cnt]) cnt++;
    rep(i,n){
        if(d[i]==elem&&cnt>0)  {out("A",""); cnt--;}
        else if(d[i]>elem)  out("A","");
        else    out("B","");
    }
    out("",endl);

    return 0;
}