SP8916 VILLAGES - Villages by the River

In a far away country there is a wide river, N villages on the left and N villages on the right side of this river (denoted by 1..N on each side). There are also M small ships, each of them connecting one village from the left and one village from the right side (in both ways). You are to organize a film festival in four of these villages: two from the left and two from the right side. Each two of these four villages must be connected by a ship (directly) if they belong to opposite sides of the river. Help yourself to choose these four villages and first find out; in how many ways can you choose them?

In the first line there are integers N In the next M lines there are two integers from the interval \[1, N\] representing the village from the left and the village from the right side connected by this ship.

Print the required number of ways to choose villages for the festival.