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

const int N = 1010;
int f[N][N];
string a, b;
int n, m;

int main()
{
    cin >> n >> m;
    cin >> a;
    cin >> b;
    a = " " + a; 
    b = " " + b;
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= m;j++)
        {
            f[i][j] = max(f[i - 1][j], f[i][j - 1]);
            if(a[i] == b[j]) f[i][j] = max(f[i][j], f[i - 1][j - 1] + 1);
        }
    cout << f[n][m] << endl;
    return 0;
}