#include <cstdio>
#include <algorithm>
#define MAXN 1000
using namespace std;

int n, m;
char s[MAXN+1], t[MAXN+1];
int dp[MAXN+1][MAXN+1];
int main()
{
	scanf("%d%d", &n, &m );
	scanf("%s", s );
	scanf("%s", t );

	// 以下为递推式
	for( int i=0; i<n; i++ )
	{
		for( int j=0; j<m; j++ )
		{
			if( s[i] == t[j] )
				dp[i+1][j+1] = dp[i][j] +1;
			else
				dp[i+1][j+1] = max( dp[i][j+1], dp[i+1][j] );
		}
	}
	printf("%d\n", dp[n][m] );


	return 0;
}