n, k = map(int, input().split())
a = list(map(int, input().split()))

dp = [0] * (k+1)
dp[0] = 1
dp[1] = 1
dp[2] = 2

for i in range(3, k+1):
dp[i] = dp[i-1] + dp[i-2] + dp[i-3]

for j in range(n):
for i in range(k, a[j]-1, -1):
dp[i] -= dp[i-a[j]-1]

print(dp[k])