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

tmax = sum(T)
dp = [False] * (tmax +1)
dp[0] = True

for t in T:
    for cur in range(tmax, t-1, -1):
        dp[cur] = dp[cur] | dp[cur-t]

G = set()
for i in range(tmax+1):
    if dp[i]:
        G.add(i)

ans = set()
for u in U:
    for g in G:
        ans.add(u+g)

print(len(ans))