#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<bitset>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<deque>
#include<list>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<functional>
using namespace std;

#define repr(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, n) repr(i, 0, n)
#define INF 2e9
#define MOD 1000000007
//#define MOD 998244353
#define LINF (long long)4e18
#define jck 3.141592

using ll = long long;
using Pi = pair<int,int>;
using Pl = pair<ll,ll>;

bool dp[5020][5020];
int N,X;
vector<int> a;
bool used[5020][5020];
vector<ll> sum;

bool solve(int l,int r){
    if(used[l][r]) return dp[l][r];
    used[l][r] = true;
    if(r-l == 1) return dp[l][r] = false;

    bool res = false;
    repr(i,l+1,r){
        if(sum[i] > X) break;
        if(!solve(i,r)) res = true;
    }
    for(int i = r-1; i >= l+1; i--){
        if(sum[r]-sum[i] > X) break;
        if(!solve(l,i)) res = true;
    }
    return dp[l][r] = res;
}

int main(){
    cin >> N >> X;
    a.resize(N);
    sum.resize(N+1);
    rep(i,5020)rep(j,5020) used[i][j] = false;
    rep(i,N) cin >> a[i];
    rep(i,N) sum[i+1] = sum[i]+a[i];
    cout << (solve(0,N)?'A':'B') << endl;
}