text: # Problem Step up and down Kazuki, commonly known as Kerr, who attends JAG University, was invited by your friend this summer to participate in the ICPC (International Collegiate Potchari Contest).ICPC is a sports contest and requires a high degree of athletic ability.However, Mr.Kerr was always in front of the computer, and he was so lacking in exercise that he was tired even if he moved a little.Therefore, Kerr decided to start an easy-to-start exercise, "stepping up and down," as the first step to achieve good results with ICPC.As the name suggests, stepping up and down is a simple exercise that simply repeats going up and down between the step and the floor.However, in stepping up and down, the effect cannot be obtained unless the feet are raised and lowered correctly.Correct ascent and descent is the movement of the foot that satisfies either of the following two types.* From the state where both feet are on the floor, the left foot and the right foot are raised on the stepping stone, and both feet are on the stepping stone.Either the left foot or the right foot may be raised first.* From the state where both feet are on the platform, the left foot and the right foot are lowered to the floor, and both feet are on the floor.Either the left foot or the right foot may be lowered first.As can be seen from the above, raising and lowering only one leg continuously from the state of being on the floor or stepping stone does not result in correct raising and lowering.In the stepping up / down movement, when any of the above correct up / down movements is satisfied, it is counted as one time, and the larger the count number, the more effective the effect can be obtained.Note that even if you don't go back and forth between the floor and the platform, it counts as one only one way.You want your teammate, Kerr, to be as strong as possible.So you decided to write a program and check if Kerr was skipping the step up and down.