After one week in Buenos Aires, it is time to go back home. You arrive at the Ezeiza International Airport two hours early since it is Monday morning and you know that there could be a lot of traffic. You debate whether to check in your baggage, but decide that it is light enough, and the effort and inconvenience of carrying it with you is less than the inconvenience of waiting for the checked in baggage to arrive when you reach your destination. Check$-$in is quick, since the airline has installed a lot of self$-$check$-$in kiosks. However, at the security checkpoint there is a long queue, and you resign yourself to a long wait. After $15$ minutes you begin to regret your decision not to check in your handbag, since it is beginning to hurt your shoulder. When you reach the end of the line, security personnel directs groups of passengers to the different security gates. You take off your shoes and take your laptop out of the case, but you have to wait for additional trays in order to put your cell phone and keys. Some other travelers who do not have to wait for trays skipped ahead of you. Fortunately your security gate was very quick. You notice that one person has to turn back and re$-$enter a number of times at another gate $$ the folks behind him were getting impatient. You board the plane and settle down for the flight. However, after taxiing to the runway, the pilot announces that due to the number of planes already waiting for departure, you will be delayed by about $20$ minutes. You can see the other planes taking off on the runway, since you always take a window seat. The couple seated next to you has a $9$ month old baby, and you chat with them about the baby$$s first steps.