N, M = map(int, input().split())
A = list(map(int, input().split()))
S = list(map(int, input().split()))
T = 0
X = 0
for s in S:
    T |= 1 << s
while S:
    U = 0
    for s in S:
        U |= T << s
    S = []
    for i in range(2 * N + 1):
        if (X >> i) & 1:
            continue
        if not (U >> i) & 1:
            continue
        X |= 1 << i
        if (T >> A[i]) & 1:
            continue
        T |= 1 << A[i]
        S.append(A[i])
print(sum(1 & (T >> i) for i in range(2 * N + 1)))