Links:
Problem A — Friends Meeting: https://youtu.be/bFEmX3y8idE
Problem B — World Cup: https://youtu.be/tzF_nagpR5A
Problem C — Laboratory Work: coming Fri 16th
Problem D — Peculiar Apple-Tree: https://youtu.be/aqVF3vpiERE
Site Links:
Codeforces Round 468 (Div. 2, based on Technocup 2018 Final Round)
931A - Friends Meeting
931B - World Cup
931D - Peculiar apple-tree