#include <iostream>
#include <vector>
#include <algorithm>

int edit_distance(const std::vector<int> &a, const std::vector<int> &b) {
    std::vector<std::vector<int>> dp(a.size() + 1, std::vector<int>(b.size() + 1, 0));
    for (int i = 0; i < a.size() + 1; ++i) {
        dp[i][0] = i;
    }
    for (int i = 0; i < b.size() + 1; ++i) {
        dp[0][i] = i;
    }
    for (int i = 0; i < a.size(); ++i) {
        for (int j = 0; j < b.size(); ++j) {
            dp[i + 1][j + 1] = std::min({dp[i + 1][j] + 1, dp[i][j] + (a[i] != b[j]), dp[i][j + 1] + 1});
        }
    }
    return dp[a.size()][b.size()];
}

int main() {
    int n, m;
    std::cin >> n >> m;
    std::vector<int> a, b;
    for (int i = 0; i < n; ++i) {
        int tmp;
        std::cin >> tmp;
        for (int j = 0; j < tmp; ++j) a.push_back(0);
        if (i != n - 1) a.push_back(1);
    }
    for (int i = 0; i < m; ++i) {
        int tmp;
        std::cin >> tmp;
        for (int j = 0; j < tmp; ++j) b.push_back(0);
        if (i != m - 1) b.push_back(1);
    }
    std::cout << edit_distance(a, b) << std::endl;
    return 0;
}