#include<iostream>
#include<cstring>
using namespace std;
const int N = 1010;
int n,m,f[N][N];
char a[N],b[N];
int main()
{
scanf("%d %d",&n ,&m);
scanf("%s%s",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);
}
printf("%d",f[n][m]);
return 0;
}