from typing import Any, Sequence


INF = int(1e18)


def min(a: int, b: int) -> int:
    return a if a < b else b


def editDistance(word1: Sequence[Any], word2: Sequence[Any]) -> int:
    n1, n2 = len(word1), len(word2)
    dp = [[INF] * (n2 + 1) for _ in range(n1 + 1)]
    dp[0][0] = 0

    for i in range(n1 + 1):
        dp[i][0] = i
    for j in range(n2 + 1):
        dp[0][j] = j

    for i in range(1, n1 + 1):
        for j in range(1, n2 + 1):
            if word1[i - 1] == word2[j - 1]:
                dp[i][j] = dp[i - 1][j - 1]
            else:
                dp[i][j] = min(dp[i - 1][j - 1] + 1, min(dp[i - 1][j] + 1, dp[i][j - 1] + 1))

    return dp[n1][n2]

from typing import List


def operation6(nums1: List[int], nums2: List[int]) -> int:
    sb1, sb2 = [], []
    for v in nums1:
        sb1.append(0)
        for _ in range(v):
            sb1.append(1)
    for v in nums2:
        sb2.append(0)
        for _ in range(v):
            sb2.append(1)

    return editDistance(sb1, sb2)


if __name__ == "__main__":
    n, m = map(int, input().split())
    nums1 = list(map(int, input().split()))
    nums2 = list(map(int, input().split()))
    print(operation6(nums1, nums2))