CF678D.Iterated Linear Function

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题目描述

Consider a linear function f(x)=Ax+Bf(x)=Ax+B . Let's define g(0)(x)=xg^{(0)}(x)=x and g(n)(x)=f(g(n1)(x))g^{(n)}(x)=f(g^{(n-1)}(x)) for n>0 . For the given integer values AA , BB , nn and xx find the value of g(n)(x)g^{(n)}(x) modulo 109+710^{9}+7 .

输入格式

The only line contains four integers AA , BB , nn and xx ( 1<=A,B,x<=109,1<=n<=10181<=A,B,x<=10^{9},1<=n<=10^{18} ) — the parameters from the problem statement.

Note that the given value nn can be too large, so you should use 6464 -bit integer type to store it. In C++ you can use the long long integer type and in Java you can use long integer type.

输出格式

Print the only integer ss — the value g(n)(x)g^{(n)}(x) modulo 109+710^{9}+7 .

输入输出样例

  • 输入#1

    3 4 1 1
    

    输出#1

    7
    
  • 输入#2

    3 4 2 1
    

    输出#2

    25
    
  • 输入#3

    3 4 3 1
    

    输出#3

    79
    
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