def edit_distance(a, b):
    dp = [[0 for j in range(len(b) + 1)] for i in range(len(a) + 1)]
    for i in range(len(a) + 1):
        dp[i][0] = i
    for i in range(len(b) + 1):
        dp[0][i] = i
    for i in range(len(a)):
        for j in range(len(b)):
            dp[i + 1][j + 1] = min([dp[i + 1][j] + 1, dp[i][j] + (a[i] != b[j]), dp[i][j + 1] + 1])
    return dp[len(a)][len(b)]

n, m = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
aa = []
for i in range(n):
    aa += [0] * a[i]
    if i != n - 1:
        aa += [1]
bb = []
for i in range(m):
    bb += [0] * b[i]
    if i != m - 1:
        bb += [1]
print(edit_distance(aa, bb))