Statement

William was supervising some kids in a big rectangular room (of size R × C meters), when he suddenly got an unexpected call from Giorgio to discuss urgent duties for the next round of the OIS. Before answering the phone, he gave the kids K rectangular carpets (numbered from 1 to K) of various sizes to play with. When the call ended, William came back to check the situation and found a giant mess of carpets lying on the floor, some even on top of others: what a disaster! However, he thought that he could turn this awful moment in a catchy Instagram post. He has already taken a picture of the room from above, but he misses the description. Of course, being a precision lover, William wants to enter a boring but accurate description: the exact coordinates of each of the carpets. Help him!