#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
using namespace std;

int n;
int m;

int dp[1002][1002];
string s;
string t;
bool use[1002][1002];
inline int dfs(int a, int b){
	if (a == s.size() && b == t.size()){
		return 0;
	}
	if (a == s.size()){
		return t.size() - b;
	}
	if (b == t.size()){
		return s.size() - a;
	}
	if (use[a][b]){
		return dp[a][b];
	}
	use[a][b] = true;
	dp[a][b] = INT_MAX;
	if (s[a] == t[b]){
		dp[a][b] = dfs(a + 1, b + 1);
	}
	
	dp[a][b] = min(dp[a][b],dfs(a + 1, b + 1) + 1);
	dp[a][b] = min(dp[a][b], dfs(a + 1, b) + 1);
	dp[a][b] = min(dp[a][b], dfs(a, b + 1) + 1);
	return dp[a][b];
}
int main(){
	cin >> n;
	cin >> m;
	cin >> s;
	cin >> t;
	int ans = dfs(0, 0);
	cout << ans << endl;
	return 0;
}