#include <bits/stdc++.h>
using namespace std;using ll = long long;
ll INF = (1LL << 60);
int main() {
	int n, m;cin >> n >> m;
	vector<int> A, B;
	for (int i = 0;i < n;i++) {
		int a;cin >> a;
		A.push_back(0);
		for (int j = 0;j < a;j++) A.push_back(1);
	}
	for (int i = 0;i < m;i++) {
		int b;cin >> b;
		B.push_back(0);
		for (int j = 0;j < b;j++) B.push_back(1);
	}
	int N = A.size();int M = B.size();
	vector<vector<ll>> dp(N + 1, vector<ll>(M + 1, INF));
	dp[0][0] = 0;
	for (int i = 1;i <= N;i++) dp[i][0] = i;
	for (int i = 1;i  <= M;i++) dp[0][i] = i;
	for (int i = 1;i <= N;i++) for(int j = 1;j <= M;j++) {
		dp[i][j] = min(dp[i][j], dp[i - 1][j - 1] + (A[i - 1] != B[j - 1]));
		dp[i][j] = min(dp[i][j], min(dp[i - 1][j], dp[i][j - 1]) + 1);
	}
	cout << dp[N][M] << endl;
}