1569  Gift
Time Limit : 1 Second
Memory Limit : 128 MB
Submission: 135
Solved: 19
 Description
 X has a necklace with N pearls.He want to label each pearl with a lucky number a (0=<L=<a<=R<10^9).Everybody knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7.To make it luckier,he make two rules.
Rule 1:any adjacent beads couldn’t have same lucky number.
an illegal situation
Rule 2:The repetitions that are produced by rotation around the center of the necklaceare all neglected.
They are the same.
Now X will give you N, L, R, he wants you to help him calculate the number of different methods, because the number of method is so huge, so X just want you to tell him the remainder when divided by M.
In this problem, M = 1,000,000,007.  Input
 The input consists of several test cases.(at most 1000)
Every case has only two integers indicating N,L,R
(0<=N<=10^9, 0<=L<=R<2^63)  Output
 For each case, you should output a single line indicates the remainder of number of different methods after divided by M.
 sample input

3 3 55 3 5 125 3 8 1076 162 78923 987460
 sample output

8 20 440 651834385
 hint
 source
 Bo YANG