#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>
#include<cstdio>
#include<cstdlib>
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

const double EPS = 1e-10;

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

int N,X; 
vector<int> a;

int dp[5050][5050];

int solve(int l,int r){
    if(dp[l][r] != -1) return dp[l][r];
    if(r-l == 1) return 0;
    ll sum = 0;
    int res = 0;
    repr(i,l+1,r){
        sum += a[i-1];
        if(sum > X) break;
        if(solve(i,r) == 0) res = 1;
    }
    ll sum2 = 0;
    for(int i = r-1; i >= l+1; i--){
        sum2 += a[i];
        if(sum2 > X) break;
        if(solve(l,i) == 0) res = 1;
    }
    return dp[l][r] = res;
}

int main(){
    cin >> N >> X;
    a.resize(N);
    rep(i,N) cin >> a[i];

    rep(i,5050)rep(j,5050) dp[i][j] = -1;
    cout << (solve(0,N)?'A':'B') << endl;
}