import collections
import heapq
import sys
from collections import defaultdict
from itertools import count, accumulate, pairwise, groupby

sys.setrecursionlimit(10 ** 6)
from typing import List, Tuple

int1 = lambda x: int(x) - 1
input = lambda: sys.stdin.readline().rstrip('\n')
ii = lambda: int(input())
vi = lambda: list(map(int, input().split()))
vi1 = lambda: list(map(int1, input().split()))


def dbg(*args, **kwargs):
    print(*(repr(arg) for arg in args), *(f'{k}: {repr(v)}' for k, v in kwargs.items()),
          sep='; ', file=sys.stderr, flush=True)


def main():
    n, m = vi()
    u = vi()
    t = vi()
    d = [True]
    for v in t:
        d.extend([False] * v)
        for i in reversed(range(len(d) - v)):
            if d[i]:
                d[i + v] = True
    e = [False] * (len(d) + max(u))
    for i in range(len(d)):
        if d[i]:
            for j in u:
                e[i + j] = True
    return sum(e)


def _start():
    if (ret := main()) is not None:
        print(*ret) if isinstance(ret, List) or isinstance(ret, Tuple) else print(ret)


if __name__ == '__main__':
    _start()