#include using namespace std; using lint = long long int; using pint = pair; struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_; #define ALL(x) (x).begin(), (x).end() #define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i=i##_begin_;i--) #define REP(i, n) FOR(i,0,n) #define IREP(i, n) IFOR(i,0,n) template bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; } template bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; } template istream &operator>>(istream &is, vector &vec){ for (auto &v : vec) is >> v; return is; } template ostream &operator<<(ostream &os, const vector &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; } template ostream &operator<<(ostream &os, const pair &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; } #define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl; constexpr int LOSE = 1; constexpr int WIN = 2; int main() { int N; lint X; cin >> N >> X; vector A(N); cin >> A; vector B(N + 1); REP(i, N) B[i + 1] = B[i] + A[i]; vector lose_lr(N, N + 1), lose_rl(N + 1, -1); vector> win_lose(N + 1, vector(N + 1)); REP(i, N) win_lose[i][i + 1] = LOSE, lose_lr[i] = i + 1, lose_rl[i + 1] = i; REP(i, N + 1) win_lose[i][i] = WIN; FOR(d, 2, N + 1) { REP(l, N - d + 1) { bool f = false; int r = l + d; int i = upper_bound(ALL(B), B[l] + X) - B.begin(); if (i >= r) f = true; if (lose_rl[r] >= 0 and lose_rl[r] <= i) f = true; auto j = lower_bound(ALL(B), B[r] - X) - B.begin(); if (j <= l) f = true; if (lose_lr[l] >= 0 and lose_lr[l] >= j) f = true; if (f) { win_lose[l][r] = WIN; } else { win_lose[l][r] = LOSE; mmax(lose_lr[l], r); mmin(lose_rl[r], l); } } } cout << (win_lose[0][N] == WIN ? "A" : "B") << endl; }