Lucky Tree
Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

One day Petya encountered a tree with *n* vertexes. Besides, the tree was weighted, i. e. each edge of the tree has weight (a positive integer). An edge is lucky if its weight is a lucky number. Note that a tree with *n* vertexes is an undirected connected graph that has exactly *n*<=-<=1 edges.

Petya wondered how many vertex triples (*i*,<=*j*,<=*k*) exists that on the way from *i* to *j*, as well as on the way from *i* to *k* there must be at least one lucky edge (all three vertexes are pairwise distinct). The order of numbers in the triple matters, that is, the triple (1,<=2,<=3) is not equal to the triple (2,<=1,<=3) and is not equal to the triple (1,<=3,<=2). 

Find how many such triples of vertexes exist.
The first line contains the single integer *n* (1<=≤<=*n*<=≤<=105) — the number of tree vertexes. Next *n*<=-<=1 lines contain three integers each: *u**i* *v**i* *w**i* (1<=≤<=*u**i*,<=*v**i*<=≤<=*n*,<=1<=≤<=*w**i*<=≤<=109) — the pair of vertexes connected by the edge and the edge's weight.
On the single line print the single number — the answer.

Please do not use the %lld specificator to read or write 64-bit numbers in С++. It is recommended to use the cin, cout streams or the %I64d specificator.
The 16 triples of vertexes from the first sample are: (1, 2, 4), (1, 4, 2), (2, 1, 3), (2, 1, 4), (2, 3, 1), (2, 3, 4), (2, 4, 1), (2, 4, 3), (3, 2, 4), (3, 4, 2), (4, 1, 2), (4, 1, 3), (4, 2, 1), (4, 2, 3), (4, 3, 1), (4, 3, 2).

In the second sample all the triples should be counted: 4·3·2 = 24.