Jzzhu and Sequences题解

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Jzzhu has invented a kind of sequences, they meet the following property:

You are given x and y, please calculate f_n modulo 1000000007 (10⁹ + 7).

Input

The first line contains two integers x and y (|x|, |y| ≤ 10⁹). The second line contains a single integer n (1 ≤ n ≤ 2·10⁹).

Output

Output a single integer representing f_n modulo 1000000007 (10⁹ + 7).

Example

Input

2 3
3

Output

1

Input

0 -1
2

Output

1000000006

Note

In the first sample, f₂ = f₁ + f₃, 3 = 2 + f₃, f₃ = 1.

In the second sample, f₂ =  - 1;  - 1 modulo (10⁹ + 7) equals (10⁹ + 6).

AC C++

#include <iostream>   
#define m 1000000007
using namespace std ;    
long long  a,b,n;  
  
int main()  
{  
    cin>>a>>b>>n;  
    n--;  
    n=n % 6;  
    long long ans=0;
    switch(n)  
    {  
        case 0:   
        {  
            ans=(a+m)%m;  
            break;  
        }  
        case 1:  
        {  
            ans=(b+m)%m;  
            break;  
        }  
        case 2:  
        {  
            ans=(b-a+2*m)%m;
            break;  
        }  
        case 3:  
        {  
            ans=(m-a)%m;  
            break;  
        }  
        case 4:  
        {  
            ans=(m-b)%m;  
            break;  
        }  
        case 5 :  
        {  
            ans=(a-b+2*m)%m;
            break;  
        }  
    }  
    cout<<ans<<endl;  
    return 0;  
}