Lele reached the third floor, Lele only climbed the second floor, and his brother reached the fifth floor, and his brother only climbed the fourth floor. Because the first floor doesn't count.
So my brother climbed the stairs twice as fast as Lele, and 4 divided by 2=2.
So Lele went to the 7th floor. In fact, Lele only climbed 6 stairs, so my brother climbed 6X2= 12 stairs. 12+ 1= 13 is my brother's floor, and the floor is 13.