#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

template<class Monoid> struct SegTree {
    using Func = function<Monoid(Monoid, Monoid)>;
    const Func F;
    const Monoid UNITY;
    ll SIZE_R;
    vector<Monoid> dat;
    
    SegTree(ll n, const Func f, const Monoid &unity): F(f), UNITY(unity) { init(n); }
    void init(ll n) {
        SIZE_R = 1;
        while (SIZE_R < n) SIZE_R *= 2;
        dat.assign(SIZE_R * 2, UNITY);
    }
    
    /* set, a is 0-indexed */
    void set(ll a, const Monoid &v) { dat[a + SIZE_R] = v; }
    void build() {
        for (ll k = SIZE_R - 1; k > 0; --k)
            dat[k] = F(dat[k*2], dat[k*2+1]);
    }
    
    /* update a, a is 0-indexed */
    void update(ll a, const Monoid &v) {
        ll k = a + SIZE_R;
        dat[k] = v;
        while (k >>= 1) dat[k] = F(dat[k*2], dat[k*2+1]);
    }
    
    /* get [a, b), a and b are 0-indexed */
    Monoid get(ll a, ll b) {
        Monoid vleft = UNITY, vright = UNITY;
        for (ll left = a + SIZE_R, right = b + SIZE_R; left < right; left >>= 1, right >>= 1) {
            if (left & 1) vleft = F(vleft, dat[left++]);
            if (right & 1) vright = F(dat[--right], vright);
        }                                                                                                              
        return F(vleft, vright);
    }
    inline Monoid operator [] (ll a) { return dat[a + SIZE_R]; }
    
    
};


const ll MAX = 110000;
const long long INF = 1LL<<60;


signed main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);

    
    ll n,x;
    cin>>n>>x;
    ll a[n];
    ll sum[n+1]={};
    for(ll i=0;i<n;i++){
        cin>>a[i];
        sum[i+1] += a[i] + sum[i];
    }
    ll rev[n+1]={};
    for(ll i=0;i<n;i++){
        rev[i+1] += rev[i] + a[n-1-i];
    }
    ll dp[n][n] = {};
    auto f = [](bool a, bool b){return a & b;};
    vector<SegTree<bool>> seg(n,SegTree<bool>(n, f, 0));
    for(ll i=n-1;i>=0;i--){
        for(ll j=i;j<n;j++){
            if(i==j) continue;
            ll ret = upper_bound(sum,sum+n+1,sum[i+1]+x) - sum;
            ret--;
            bool pos = seg[i].get(i+1,ret);
            if(!pos) dp[i][j] = 1;
            ret = rev+n-upper_bound(rev,rev+n+1,rev[j]+x);
            ret++;
            pos = seg[j].get(ret ,j);
            if(!pos) dp[i][j] = 1;
            seg[i].update(j,dp[i][j]);
            seg[j].update(i,dp[i][j]);
        }
    }
    if(dp[0][n-1]){
        cout << "A\n";
    }
    else cout << "B\n";
}