#include <bits/stdc++.h>
using namespace std;
const long long MAXN = 2e5 + 10, MOD = 1e9 + 7;
long long n, T, ni[MAXN], jie[MAXN], jie_ni[MAXN], A[MAXN], ans, sum;
long long sum_N, sum_K;
void Init() {
  ni[1] = 1;
  for (long long i = 2; i <= MAXN - 10; i++) {
    ni[i] = ((MOD - (MOD / i)) * ni[MOD % i] % MOD) % MOD;
  }
  jie_ni[0] = 1;
  for (long long i = 1; i <= MAXN - 10; i++) {
    jie_ni[i] = jie_ni[i - 1] * ni[i] % MOD;
  }
  jie[0] = 1;
  for (long long i = 1; i <= MAXN - 10; i++) {
    jie[i] = jie[i - 1] * i % MOD;
  }
}
long long Quick(long long x, long long y) {
  long long res = 1, a = x;
  while (y) {
    if (y & 1) res *= a, res %= MOD;
    a = a * a, a %= MOD;
    y /= 2;
  }
  return res;
}
long long C(long long x, long long y) {
  if (y == 0) return 1;
  if (x == y) return 1;
  return (jie[x] * jie_ni[y]) % MOD * jie_ni[x - y] % MOD;
}
long long work(long long N, long long K) {
  if (sum_N == 0) {
    sum_N = 1;
    for (long long i = 1; i <= K; i++) sum_N += C(N, i), sum_N %= MOD;
    sum_K = K;
    return sum_N;
  } else {
    sum_N = (sum_N * 2 - C(N - 1, sum_K) + MOD) % MOD;
    for (long long i = sum_K; i >= K + 1; i--) {
      sum_N -= C(N, i), sum_N = (sum_N + MOD) % MOD;
    }
    sum_K = K;
    return sum_N;
  }
}
signed main() {
  cin >> n >> T;
  Init();
  for (long long i = 1; i <= n; i++) cin >> A[i];
  long long BASE = 1;
  for (long long i = 1; i <= n; i++) {
    sum += A[i];
    BASE = BASE * 2;
    BASE %= MOD;
    if (T - sum >= i) {
      ans++;
      ans %= MOD;
    } else if (T - sum < 0) {
      break;
    } else {
      ans += (work(i, T - sum) * Quick(BASE, MOD - 2)) % MOD;
      ans %= MOD;
    }
  }
  cout << ans;
  return 0;
}
