Consider the following mini-world. A person has a name and an age. Cities have a name and are located in a country. Every year, persons can form groups in order to travel together to a city. A person may be part of the same or a
different group in different years, but may be part of at most one group in any given year. Furthermore, a group travels
to the same or different city in different years, but travels to exactly one city in any given year. Give an ER model for
this mini-world. Identify the keys and give the cardinalities of all relationships (e. g., 1:1, N:1, N:M).