Mathematical Olympiad | Training Book Level 1 Pdf
  中国科学院大学学报 mathematical olympiad training book level 1 pdf 2021, Vol. 38 mathematical olympiad training book level 1 pdfIssue (5): 611-623 mathematical olympiad training book level 1 pdf mathematical olympiad training book level 1 pdf  PDF    

Mathematical Olympiad | Training Book Level 1 Pdf

Problem (Combinatorics, Easy): Show that among any 6 integers, there exist two with difference divisible by 5.