#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1010;
int n,m;
char a[N],b[N];
int f[N][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\n", f[n][m]);
return 0;
}