#include <bits/stdc++.h>
using namespace std;
inline long long read() {
  long long x = 0, f = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9')
    x = (x << 3) + (x << 1) + (c ^ '0'), c = getchar();
  return x * f;
}
const int N = 3e5 + 5, mod = 1e9 + 7;
inline int inc(int x, int y) {
  x += y - mod;
  return x + (x >> 31 & mod);
}
inline int del(int x, int y) {
  x -= y;
  return x + (x >> 31 & mod);
}
inline int mul(int x, int y) { return 1ll * x * y % mod; }
inline void Inc(int &x, int y) { x = inc(x, y); }
inline void Del(int &x, int y) { x = del(x, y); }
inline void Mul(int &x, int y) { x = mul(x, y); }
inline long long Pow(long long x, long long k) {
  long long res = 1;
  while (k) {
    if (k & 1) res = res * x % mod;
    x = x * x % mod;
    k >>= 1;
  }
  return res;
}
int inv[N], fac[N], inv2[N];
inline void init(int n) {
  fac[0] = inv[0] = 1;
  for (int i = 1; i <= n; i++) fac[i] = mul(fac[i - 1], i);
  inv[n] = Pow(fac[n], mod - 2);
  for (int i = n - 1; i >= 1; i--) inv[i] = mul(inv[i + 1], i + 1);
  int fac2 = 1;
  for (int i = 1; i <= n; i++) Inc(fac2, fac2);
  inv2[n] = Pow(fac2, mod - 2);
  for (int i = n - 1; i >= 1; i--) inv2[i] = inc(inv2[i + 1], inv2[i + 1]);
}
inline int C(int n, int m) {
  if (n < m) return 0;
  return 1ll * fac[n] * inv[m] % mod * inv[n - m] % mod;
}
int n, ans;
long long s, T;
int main() {
  n = read();
  T = read();
  init(n);
  int j = n, sum = 1;
  for (int i = 1; i <= n; i++) {
    int x = read();
    s += x;
    if (s > T) continue;
    int l = min(1ll * n, T - s);
    sum = del(inc(sum, sum), C(i - 1, j));
    while (j > l) Del(sum, C(i, j)), j--;
    Inc(ans, mul(inv2[i], sum));
  }
  printf("%d\n", ans);
  return 0;
}
