little boy Petya love stair but bored simple going loves jump stair time as stand stair jump jump stair time but stair dirty Petya do not want step themnow petya stair staircase consist n stair he know number dirty stair staircase Help Petya find jump entire staircase reach stair number n touch dirty stair onceone note Petya step stair stair dirty Petya choose path clean step