#include<bits/stdc++.h>
#define REP(i,n) for(int i=0,i##_len=int(n);i<i##_len;++i)
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
#define All(x) (x).begin(),(x).end()
#define rAll(x) (x).rbegin(),(x).rend()
using namespace std;
using ll = long long;
 template<typename T>
    bool chmin(T &a,T b){
        if(b<a){
            a=b;
            return true;
        }
        return false;
    }
int main(){
    int N,X;cin>>N>>X;
    vector<int> a(N);
    REP(i, N) cin >> a[i];
    vector<vector<int>> win(N,vector<int>(N,X+1));
    REP(i,N) win[i][i]=X+1;
    rep(k,1,N) REP(i,N){
        if(i-k>=0){
            int res=win[i-k+1][i]+a[i-k];
            if(res-a[i-k]==X+1) chmin(win[i-k][i],a[i-k]);
            else if(res<=X) chmin(win[i-k][i],res);
        }
        if(i+k<N){
            int res=win[i][i+k-1]+a[i+k];
            if(res-a[i+k]==X+1) chmin(win[i][i+k],a[i+k]);
            else if(res<=X) chmin(win[i][i+k],res);
        }
    }
    if(win[0][N-1]==X+1) cout<<"B"<<endl;
    else cout<<"A"<<endl;
}