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

int edit_distance(string& s, string& t) {
    vector<vector<int>> dp(s.size() + 1, vector<int>(t.size() + 1));
    for (int i = 0; i <= s.size(); i++) {
        for (int j = 0; j <= t.size(); j++) {
            if (i == 0) {
                dp[i][j] = j;
            } else if (j == 0) {
                dp[i][j] = i;
            } else {
                dp[i][j] = INT_MAX;
            }
        }
    }

    for (int i = 1; i <= s.size(); i++) {
        for (int j = 1; j <= t.size(); j++) {
            if (s[i - 1] == t[j - 1]) {
                dp[i][j] = dp[i - 1][j - 1];
            } else {
                dp[i][j] = min({dp[i - 1][j], dp[i][j - 1], dp[i - 1][j - 1]}) + 1;
            }
        }
    }
    return dp[s.size()][t.size()];
}

int main() {
    int n, m;
    cin >> n >> m;
    string s, t;
    cin >> s >> t;
    cout << edit_distance(s, t) << endl;
}