#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=1010;
int f[N][N];
char a[N],b[N];

signed 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-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;
}