#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
typedef pair<int,P> P1;
typedef pair<P,P> P2;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 1000000000
#define mod 1000000007
#define fi first
#define sc second
#define rep(i,x) for(int i=0;i<x;i++)
#define repn(i,x) for(int i=1;i<=x;i++)
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())
int n,x,a[5005];
struct BIT
{
	short bit[5005];
	void add(int i,short x)
	{
		for(int s=i;s<5005;s+=s&-s) bit[s]+=x;
	}
	short sum(int i)
	{
		short res=0;
		for(int s=i;s>0;s-=s&-s) res+=bit[s];
		return res;
	}
}bitL[5005],bitR[5005];

bool dp[5005][5005];
int goL[5005],goR[5005];
int main(){
	scanf("%d%d",&n,&x);
	repn(i,n) scanf("%d",&a[i]);
	repn(i,n){
		goL[i] = n;
		ll sum = 0;
		for(int j=i;j<=n;j++){
			sum += a[j];
			if(sum > x){
				goL[i] = j-1; break;
			}
		}
		goR[i] = 1;
		sum = 0;
		for(int j=i;j>=0;j--){
			sum += a[j];
			if(sum > x){
				goR[i] = j+1; break;
			}
		}
	}
	for(int len=1;len<=n;len++){
		for(int i=1;i+len-1<=n;i++){
			int L = i, R = i+len-1;
			int x = min(goL[L],R-1);
			if(L <= x){
				if(bitR[R].sum(x+1) > bitR[R].sum(L)){
					dp[L][R] = 1; goto nxt;
				}
			}
			x = max(goR[R],L+1);
			if(x <= R){
				if(bitL[L].sum(R-1) > bitL[R].sum(x-2)){
					dp[L][R] = 1; goto nxt;
				}
			}
			bitL[L].add(R,1);
			bitR[R].add(L,1);
			nxt:;
		}
	}
	puts(dp[1][n]?"A":"B");
}