#include <bits/stdc++.h>
using namespace std;

const int N=1005;
int f[N][N];
int n,m;

int main(){
    memset(f, 0x00, sizeof f);
    cin>>n>>m;
    string a, b;
    cin>>a>>b;

    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-1]==b[j-1])
                f[i][j]=max(f[i][j], f[i-1][j-1]+1);
        }

    cout<<f[n][m]<<endl;

    return 0;
}