#include<iostream>

using namespace std;

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

int main()
{
    cin >> n >> m >> a+1 >> b+1;

    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;
}