#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;
}