CF717A.Festival Organization

普及/提高-

通过率:0%

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题目描述

The Prodiggers are quite a cool band and for this reason, they have been the surprise guest at the ENTER festival for the past 80 years. At the beginning of their careers, they weren’t so successful, so they had to spend time digging channels to earn money; hence the name. Anyway, they like to tour a lot and have surprising amounts of energy to do extremely long tours. However, they hate spending two consecutive days without having a concert, so they would like to avoid it.

A tour is defined by a sequence of concerts and days-off. You need to count in how many ways The Prodiggers can select kk different tours of the same length between ll and rr .

For example if k=2k=2 , l=1l=1 and r=2r=2 , if we define concert day as {1} and day-off as {0}, here are all possible tours: {0}, {1}, {00}, {01}, {10}, {11}. But tour 00 can not be selected because it has 22 days-off in a row. Now, we need to count in how many ways we can select k=2k=2 tours of the same length in range [1;2][1;2] . Here they are: {0,1}; {01,10}; {01,11}; {10,11}.

Since their schedule is quite busy, they want you to tell them in how many ways can do that, modulo 10000000071000000007 ( 109+710^{9}+7 ).

输入格式

The first line of the input contains three integers kk , ll and rr ( 1<=k<=2001<=k<=200 , 1<=l<=r<=10181<=l<=r<=10^{18} ).

输出格式

Output a single number: the number of ways to select kk different tours of the same length, modulo 10000000071000000007 .

输入输出样例

  • 输入#1

    1 1 2
    

    输出#1

    5
    
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