#include <bits/stdc++.h> #include <atcoder/all> using namespace std; using namespace atcoder; typedef long long int ll; typedef long double ld; #define FOR(i,l,r) for(ll i=l;i<r;i++) #define REP(i,n) FOR(i,0,n) #define RFOR(i,l,r) for(ll i=r-1;i>=l;i--) #define RREP(i,n) RFOR(i,0,n) #define ALL(x) x.begin(),x.end() #define P pair<ll,ll> #define F first #define S second #define BS(A,x) binary_search(ALL(A),x) #define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin()) #define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin()) #define COU(A,x) UB(A,x)-LB(A,x) template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>; using mint=modint1000000007; //using mint=modint998244353; void chmax(ll&a,ll b){a=max(a,b);} signed main(){ ll N,K;cin>>N>>K; vector<P>X(N);REP(i,N)cin>>X[i].F;string ans; REP(i,N){ll b;cin>>b;X[i].F-=b;X[i].S=i;ans+='B';} sort(ALL(X));reverse(ALL(X));REP(i,K)ans[X[i].S]='A'; cout<<ans<<endl; return 0; }