#include <iostream>

using namespace std;
int n,m;
const int N=1005;
int f[N][N];
char a[N],b[N];
int main()
{
    cin>>n>>m;
    cin>>a+1;
    cin>>b+1;
    for(int i=1;i<=n;i++)
    for(int j=1;j<=m;j++){
        //忽略00情况
        f[i][j]=max(f[i][j-1],f[i-1][j]);
        if(a[i]==b[j]) f[i][j]=max(f[i][j],f[i-1][j-1]+1);
    }
    cout<<f[n][m];
    //cout << "Hello world!" << endl;
    return 0;
}