#include<iostream>
#include<cstring>
#include<algorithm>
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];
    return 0;
}