#yuki616

f=[0 for i in xrange(100001)]
s=[0 for i in xrange(100001)]
t=[0 for i in xrange(100001)]
mod=10**9+7
n,k=map(int,raw_input().split())
dmy=map(int,raw_input().split())
f[0]=1
for i in xrange(n):
 for j in xrange(100000):
  s[j+1]=(s[j]+f[j])%mod
  if j-i>=0:
   t[j]=(s[j+1]-s[j-i]+mod)%mod
  else:
   t[j]=(s[j+1]+mod)%mod
 f,t=t,f
res=0
for i in xrange(k+1):
 res+=f[i]
print res%mod