# A Snake-y Problem

**Discrete Mathematics**Level 4

A boy is standing at the foot of a flight of stairs. He has to reach to the \({ 9 }^\text{ th }\) stair by taking steps of 1 or 2 only. He would have done it easily if there wasn't a snake of the \({7}^\text{th}\) stair. What is the number of ways in which he can get to the \({9}^\text{th}\) stair while avoiding the \({7}^\text{th}\) stair?