N, K = map(int, input().split())
A = list(map(int, input().split()))

# import random
# N = 100
# K = 10**5
# A = [K] * N

if sum(A) < K:
  print(0)
  exit(0)


class SegmentTree:
    def __init__(self, array, operator, identity_element):
        _len = len(array)
        self.__op = operator
        self.__size = 1 << (_len - 1).bit_length()
        self.__tree = [identity_element] * self.__size + \
            array + [identity_element] * (self.__size - _len)
        self.__ie = identity_element

        for i in range(self.__size - 1, 0, -1):
            self.__tree[i] = operator(
                self.__tree[i * 2], self.__tree[i * 2 + 1])

    def update(self, i, v):
        i += self.__size
        self.__tree[i] = v
        while i:
            i //= 2
            self.__tree[i] = self.__op(
                self.__tree[i * 2], self.__tree[i * 2 + 1])

    def query(self, l, r):
        l += self.__size
        r += self.__size
        ret = self.__ie
        while l < r:
            if l & 1:
                ret = self.__op(ret, self.__tree[l])
                l += 1
            if r & 1:
                r -= 1
                ret = self.__op(ret, self.__tree[r])
            l //= 2
            r //= 2
        return ret


from operator import add

t0 = [0] * (K+1)
t0[0] = 1

M = 10**9 + 7
for i in range(N):
    a = A[i]
    t1 = [0] * (K+1)
    st = SegmentTree(t0, add, 0)
    for k in range(K+1):
        t1[k] = st.query(max(0, k-a), k+1) % M
    t0 = t1

print(t0[K])
