#include <bits/stdc++.h>
using namespace std;
#define modulo 1000000007
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 10000000000000000



int main(){
	
	int N,X;
	cin>>N>>X;
	
	vector<int> a(N);
	for(int i=0;i<N;i++){
		cin>>a[i];
	}
	
	vector<int> left(N),right(N);
	
	int l = 0;
	int r = 0;
	int sum = 0;
	
	while(true){
		while(r != N && sum + a[r] <= X){
			sum += a[r];
			r++;
		}
		left[l] = r-l;
		sum -= a[l];
		l++;
		if(l==N)break;
	}
	
	l=N-1;
	r=N-1;
	sum=0;
	
	while(true){
		while(l!=-1&&sum+a[l]<=X){
			sum += a[l];
			l--;
		}
		right[r] = r-l;
		sum -= a[r];
		r--;
		if(r<0)break;
	}
	
	vector<vector<bool>> dp(N,vector<bool> (N,true));
	
	for(int i=0;i<N;i++){
		for(int j=0;j<N;j++){
			l = j;
			r = j+i;
			if(r>=N)break;
			bool f = false;
			for(int k=0;k<min(i,left[l]);k++){
				if(!dp[l+k+1][r]){
					f=true;
					break;
				}
			}
			if(f==false){
				for(int k=0;k>min(i,right[r]);k++){
					if(!dp[l][r-k-1]){
						f=true;
						break;
					}
				}
			}
			dp[j][j+i]=f;
		}		
	}

	
	if(!dp[0][N-1]){
		cout<<"B"<<endl;
	}
	else{
		cout<<"A"<<endl;
	}
	
	


	return 0;
}