A man $P$ has 7 friends, 4 of them are ladies and 3 are men, His wife $Q$ also has 7 friends, 3 of them are ladies and 4 are men. Assume $P$ and $Q$ have no common friends. Then the total number of ways in which $P$ and $Q$ together can throw a party inviting 3 ladies and 3 men, so that 3 friends of each of $P$ and $Q$ are in this party, is