N, M = [int(s) for s in input().split()]
U = [int(s) for s in input().split()]
T = [int(s) for s in input().split()]

dp = 1
for t in T:
    dp |= dp << t

cand = set()

for d in range(dp.bit_length()):
    if (dp >> d) & 1 == 1:
        cand.update([d + u for u in U])

print(len(cand))