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

dp = [False]*(10**5+1)
dp[0] = True
for t in T:
    for i in reversed(range(10**5+1)):
        if i+t <= 10**5:
            dp[i+t] |= dp[i]

ans = 0
dp2 = [False]*(10**5*2+1)
for u in U:
    for i in range(10**5+1):
        if dp[i]:
            dp2[u+i] = True

print(sum(dp2))