def DFS(G):
    stack = []
    visited = [ 0 for i in range(len(G)) ]
    stack.append(0)
    while len(stack) > 0:
        current = stack.pop()
        visited[current] = 1
        print(current, end=" ")
        for j in reversed(G[current]):
            if visited[j] == 0:
               stack.append(j)

DFS([ [2,4,5], [2,3,5], [0,1,3,4,5], [1,2], [0,2,6], [0,1,2], [4] ])