9th Mexican Mathematical Olympiad Problems 1995

9th Mexican Mathematical Olympiad Problems 1995A1.  N students are seated at desks in an m x n array, where m, n ≥ 3. Each student shakes hands with the students who are adjacent horizontally, vertically or diagonally. If there are 1020 handshakes, what is N? A2.  6 points in the plane have the property that 8 of the distances between them are 1. Show that