Given pairwise distinct positive integers each less than . Prove that among their pairwise differences there are at least four equal numbers.

- March 12th 2012, 10:07 PMabhishekkgppairwise differences of 20 +ve int. all < 70. At least 4 are equal.
Given pairwise distinct positive integers each less than . Prove that among their pairwise differences there are at least four equal numbers.