import sys

sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 62)

# md = 10**9+7
md = 998244353

n, m = LI()
aa = []
for a in LI(): aa += [1]*a+[0]
bb = []
for a in LI(): bb += [1]*a+[0]
n, m = len(aa), len(bb)

def chmin(i, j, val):
    if val < dp[i][j]: dp[i][j] = val

dp = [[inf]*(m+1) for _ in range(n+1)]
dp[0][0] = 0
for i in range(n+1):
    for j in range(m+1):
        pre = dp[i][j]
        if i < n and j < m: chmin(i+1, j+1, pre+(aa[i] ^ bb[j]))
        if i < n: chmin(i+1, j, pre+1)
        if j < m: chmin(i, j+1, pre+1)

print(dp[n][m])