#include <bits/stdc++.h>

using namespace std;
using ll = long long;
const int INF = 1<<29;
int main() {

    int a = 0;
    cin >> a >> a;
    string S, T;
    cin >> S >> T;
    int N = max(S.size(),T.size());

    vector<vector<int> > dp(1+S.size(),vector<int>(1+T.size(),INF));
    dp.at(0).at(0) = 0;
    for (size_t i = 0; i < S.size(); i++)
    {
        for (size_t j = 0; j < T.size(); j++)
        {
            if(S.at(i) == T.at(j)){
                dp.at(i+1).at(j+1) = dp.at(i).at(j);
            }
            else
            {
                dp.at(i+1).at(j+1) = min(dp.at(i).at(j)+1,min(dp.at(i).at(j+1)+1,dp.at(i+1).at(j)+1));
            }
            
        }
        
    }
    cout << dp.at(S.size()).at(T.size()) << endl;
    

    return 0;
}