Shweta is competing in a group stair-climbing relay challenge with two of her friends. They will take turns climbing the stairs of two of the tallest buildings of the city. The three of them each plan to climb an equal number of stairs, and Shweta will go first. The first building has s stairs, and the second building has 3639 stairs. During the race, Shweta faces anaemia and is only able to complete 75% of her goal. What is the total number of stairs that she climbs?