# dp解法
N, M = map(int, input().split())
U = list(map(int, input().split()))
T = list(map(int, input().split()))
Ts = sum(T)
dp = [[0] * (Ts + 1) for _ in range(M+1)]
dp[0][0] = 1
for i in range(M):
    for j in range(Ts + 1):
        if dp[i][j] == 0:
            continue
        dp[i+1][j] = 1
        dp[i+1][j + T[i]] = 1

li = []
for i in range(Ts + 1):
    if dp[M][i] == 1:
        li.append(i)

ans = set()
for i in U:
    for j in li:
        ans.add(i + j)
ans = len(ans)
print(ans)