Loop to find the number the number of ways to reach Nth stair
for i in range ( 4 , n + 1 ) : NEW_LINE INDENT includes_3 [ i ] = includes_3 [ i - 1 ] + includes_3 [ i - 2 ] + not_includes_3 [ i - 3 ] NEW_LINE not_includes_3 [ i ] = not_includes_3 [ i - 1 ] + not_includes_3 [ i - 2 ] NEW_LINE DEDENT return includes_3 [ n ] NEW_LINE