#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1e3 + 10;
int n, m;
char a[N], b[N];
int dp[N][N];
int main()
{
cin >> n >> m;
cin >> a + 1 >> b + 1;
for(int i = 1; i <= n; i ++ )
for(int j = 1; j <= m; j ++ )
{
dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]);
dp[i][j] = max(dp[i][j], dp[i - 1][j - 1] + (a[i] == b[j]));
}
cout << dp[n][m] << endl;
return 0;
}