#include <bits/stdc++.h>
using namespace std;

int main() {
	int n, m;
	cin >> n >> m;
	string as = "", bs = "";
	for(int i = 0; i < n; i++) {
		as.push_back('0');
		int a;
		cin >> a;
		while(a--) as.push_back('1');
	}
	for(int i = 0; i < m; i++) {
		bs.push_back('0');
		int b;
		cin >> b;
		while(b--) bs.push_back('1');
	}

	n = as.size(), m = bs.size();
	vector dp(n + 1, vector(m + 1, 0));
	for(int i = 0; i <= n; i++) dp[i][0] = i;
	for(int j = 0; j <= m; j++) dp[0][j] = j;

	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= m; j++) {
			dp[i][j] = min({dp[i - 1][j] + 1, dp[i][j - 1] + 1, dp[i - 1][j - 1] + (as[i - 1] != bs[j - 1])});
		}
	}

	cout << dp.back().back() << '\n';
}