#include <bits/stdc++.h>
using namespace std;
#define REP(i,a) for(int i = 0; i < (a); i++)
#define ALL(a) (a).begin(),(a).end()
typedef long long ll;
typedef pair<int, int> P;
const int INF = 1e9;
const long long LINF = 1e18;
const long long MOD = 1e9 + 7;

#define MAX_N 5000

int n;
ll x;
ll a[MAX_N];
int dp[MAX_N + 1][MAX_N + 1][2];

bool rec(int l, int r, bool A){
    if(dp[l][r][A] != -1) return dp[l][r][A];
    if(l > r) return A;
    ll now = 0;
    if(A){
        bool res = false;
        for(int i = l; i <= r; i++){
            if(now + a[i] > x) break;
            res |= rec(i + 1, r, !A);
        }
        now = 0;
        for(int i = r; i >= l; i--){
            if(now + a[i] > x) break;
            res |= rec(l, i - 1, !A);
        }
        return dp[l][r][A] = res;
    }else{
        bool res = false;
        for(int i = l; i <= r; i++){
            if(now + a[i] > x) break;
            res |= !rec(i + 1, r, !A);
        }
        now = 0;
        for(int i = r; i >= l; i--){
            if(now + a[i] > x) break;
            res |= !rec(l, i - 1, !A);
        }
        return dp[l][r][A] = !res;
    }
}

signed main(){
    cin >> n >> x;
    REP(i,n){
        cin >> a[i];
    }
    memset(dp, -1, sizeof(dp));
    if(rec(0, n - 1, true)){
        cout << "A" << endl;
    }else{
        cout << "B" << endl;
    }
    return 0;
}