#include<iostream>
#include<algorithm>
using namespace std;
const int N=1010;

int f[N][N];
char a[N],b[N];
int main()
{
    int n,m;
    cin>>n>>m;
    cin>>a+1>>b+1;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
         {
             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]<<endl;
    return 0;
}