#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
int dp[5050][5050];
int s1[5050][5050];
int s2[5050][5050];
ll a[5050];
ll s[5050];
int n;
ll x;

int main()
{
	int n;
	ll x;
	cin>>n>>x;
	for(int i=0; i<n; i++){
		cin>>a[i];
		s[i+1]=s[i]+a[i];
	}
	for(int i=0; i<n; i++) dp[i][i]=1;
	for(int d=1; d<n; d++){
		for(int i=0; i+d<n; i++){
			int l=i, r=i+d;
			int k=upper_bound(s, s+n+1, s[l]+x)-s;
			k-=2;
			k=min(k, r-1);
			if(s1[l+1][r]-s1[k+2][r]>0){
				dp[l][r]=0;
				s1[l][r]=s1[l+1][r]+dp[l][r];
				s2[l][r]=s2[l][r-1]+dp[l][r];
				continue;
			}
			k=lower_bound(s, s+n+1, s[r+1]-x)-s;
			k=max(k, l+1);
			if(s2[l][r-1]-s2[l][k-2]>0){
				dp[l][r]=0;
			}else{
				dp[l][r]=1;
			}
			s1[l][r]=s1[l+1][r]+dp[l][r];
			s2[l][r]=s2[l][r-1]+dp[l][r];
		}
	}
	if(dp[0][n-1]) cout<<"B"<<endl;
	else cout<<"A"<<endl;
	return 0;
}