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

mod=10**9+7

DP=[1,1]

for i in range(3,N+1):
    NDP=[0]*(i*(i-1)//2+1)

    for j in range(i):
        for k in range(len(DP)):
            NDP[j+k]=(NDP[j+k]+DP[k])%mod

    DP=NDP

print(sum(DP[:K+1])%mod)