#include<iostream>
using namespace std;

const int N=1010;
char a[N],b[N];
int f[N][N];

int main(){
    int n,m;
    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];
}