Consider a directed graph G$,$ where each edge is colored either red, white, or blue. A walk in G is called a French $$ag walk if its sequence of edge colors is red, white, blue, red, white,blue, and so on$.$ More formally, a walk v$0,$v$1,...,$ vk is a French $$ag walk if$,$ for every integer i$,$ the edge $($vi; vi$+1)$ is red $($resp$.,$ white, blue$)$ if i mod $3=0($resp$.,1,2).$ Design a linear$-$time algorithm to find all nodes in G that can be reached from a given nodes through a French flag walk.