4 // there are 4 tables
4 // each table can sit 4 guests
15 // there are 15 guests
Andy  // guests' names
Bob
Cathy
David
Ethan
Frank
Gareth
Hugh
Irene
Jack
Ken
Liam
Mary
Nathan
Owen
3 // there are three pairs, each pair must be placed on the same table
Cathy Ethan
David Frank
Irene Nathan
4 // there are four pairs, each pair must be seated on different tables
Andy Frank
Hugh Owen
Gareth Ken
Hugh Mary