N,M=map(int,input().split())
U=list(map(int,input().split()))
T=list(map(int,input().split()))

S=[[False]*(100000+1) for i in range(M+1)]
S[0][0]=True
for i in range(M):
    for j in range(100001):
        if not S[i][j]:
            continue
        S[i+1][j]=True
        S[i+1][j+T[i]]=True

can=set()
for i in range(N):
    for j in range(100001):
        if S[-1][j]:
            can.add(j+U[i])

print(len(can))