#include <bits/stdc++.h>
using namespace std;
using LL = long long int;
#define incID(i, l, r) for(int i = (l)    ; i <  (r); ++i)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); ++i)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); --i)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); --i)
#define inc(i, n)  incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec(i, n)  decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))
#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define  ALL(v)  v.begin(),  v.end()
#define RALL(v) v.rbegin(), v.rend()
auto setmin   = [](auto & a, auto b) { return (b <  a ? a = b, true : false); };
auto setmax   = [](auto & a, auto b) { return (b >  a ? a = b, true : false); };
auto setmineq = [](auto & a, auto b) { return (b <= a ? a = b, true : false); };
auto setmaxeq = [](auto & a, auto b) { return (b >= a ? a = b, true : false); };
auto fl = [](auto a, auto b) { assert(b != 0); return a / b - (a % b != 0 && ((a >= 0) != (b >= 0)) ? 1 : 0); };
auto ce = [](auto a, auto b) { assert(b != 0); return a / b + (a % b != 0 && ((a >= 0) == (b >= 0)) ? 1 : 0); };
auto mo = [](auto a, auto b) { assert(b != 0); a %= b; if(a < 0) { a += abs(b); } return a; };
LL gcd(LL a, LL b) { return (b == 0 ? a : gcd(b, a % b)); }
LL lcm(LL a, LL b) { return a / gcd(a, b) * b; }
#define bit(b, i) (((b) >> (i)) & 1)
#define SI(v) static_cast<int>(v.size())
#define RF(e, v) for(auto & e: v)
#define until(e) while(! (e))
#define if_not(e) if(! (e))
#define ef else if
#define UR assert(false)

// ---- ----

#define LB(v, x) (lower_bound(ALL(v), x) - v.begin())
#define UB(v, x) (upper_bound(ALL(v), x) - v.begin())

template<typename T> T MV(T v) { return v; }
template<typename T, typename... R> auto MV(T v, int s, R... r) { return vector<decltype(MV(v, r...))>(s, MV(v, r...)); }

int main() {
	LL n, x;
	cin >> n >> x;
	vector<LL> a(n), s(n + 1), L(n), R(n);
	inc(i, n) { cin >> a[i]; }
	inc(i, n) { s[i + 1] = s[i] + a[i]; }
	
	inc(i, n) { L[i] = LB(s, s[i    ] - x) - 1; }
	inc(j, n) { R[j] = UB(s, s[j + 1] + x) - 1; }
	
	auto dp = MV(0, 2, n, n);
	auto p = [&](int k, int i, int j, int v) {
		if_not(inID(i, 0, n)) { return; }
		if_not(inID(j, 0, n)) { return; }
		dp[k][i][j] += v;
	};
	auto add = [&](int k, int i, int j, int I, int J) {
		p(k, i, j, -1);
		p(k, I, j, +1);
		p(k, i, J, +1);
		p(k, I, J, -1);
	};
	inc(d, n) {
	inc(i, n) {
		int j = i + d;
		if_not(j < n) { continue; }
		if(d > 0) {
			dp[0][i][j] += dp[0][i + 1][j] + dp[0][i][j - 1] - dp[0][i + 1][j - 1];
			dp[1][i][j] += dp[1][i + 1][j] + dp[1][i][j - 1] - dp[1][i + 1][j - 1];
		}
		if(dp[1][i][j] == 0) { add(0, i - 1, j + 1, L[i], j); add(0, i - 1, j + 1, i, R[j]); }
		if(dp[0][i][j] == 0) { add(1, i - 1, j + 1, L[i], j); add(1, i - 1, j + 1, i, R[j]); }
	}
	}
	
	cout << (dp[0][0][n - 1] != 0 ? "A" : "B") << endl;
	
	return 0;
}