#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
const int INF = (1<<30);
const ll INFLL = (1ll<<60);
const ll MOD = (ll)(1e9+7);

#define l_ength size

void mul_mod(ll& a, ll b){
	a *= b;
	a %= MOD;
}

void add_mod(ll& a, ll b){
	a = (a<MOD)?a:(a-MOD);
	b = (b<MOD)?b:(b-MOD);
	a += b;
	a = (a<MOD)?a:(a-MOD);
}

int dp[5555][5555];
ll s[5555];

int main(void){
	int i,j,n;
	ll a,x;
	cin >> n >> x;
	fill(dp[0],dp[5555],-1);
	for(i=0; i<n; ++i){
		cin >> a;
		s[i+1] = s[i]+a;
	}
	for(i=1; i<n; ++i){
		for(j=0; j<n; ++j){
			if(dp[j][j+i]<0 && dp[j+i][j]<0){
				dp[j][j+i+1] = max(j+i,dp[j][j+i+1]);
				if(j){
					if(dp[j+i][j-1]<0){
						dp[j+i][j-1] = j;
					}else{
						dp[j+i][j-1] = min(j,dp[j+i][j-1]);
					}
				}
			}
			if(!(dp[j][j+i]<0)){
				if(s[j+i+1]-s[dp[j][j+i]]<=x){
					dp[j][j+i+1] = max(dp[j][j+i+1],dp[j][j+i]);
				}
			}
			if(!(dp[j+i][j]<0) && j){
				if(s[dp[j+i][j]-1] - s[j-1] <=x){
					if(dp[j+i][j-1]<0){
						dp[j+i][j-1] = dp[j+i][j];
					}else{
						dp[j+i][j-1] = min(dp[j+i][j-1],dp[j+i][j]);
					}
				}
			}
		}
	}
	cout << ((dp[0][n]<0 && dp[n][0]<0)?"B":"A") << endl;
	return 0;
}