B. Jzzhu and Sequences

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本文介绍了一种名为B.Jzzhu的特殊序列，并提供了一个计算该序列第n项值的算法实现，输入为序列的前两项x和y，及求值的位置n，输出为序列第n项对1000000007取模后的结果。

B. Jzzhu and Sequences

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

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

$\text{[math]}$

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).

Sample test(s)

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).

#include<stdio.h>
#include<string.h>

int main()
{
    int n, m, k;
    int a[20];
    scanf("%d%d", &n, &m);
    a[1]=n;
    a[2]=m;
    scanf("%d", &k);
    for(int i=3; i<=6; i++)
    {
        a[i]=a[i-1]-a[i-2];
    }
    a[0]=a[6];
    printf("%d\n", (((a[k%6]%1000000007)+1000000007)%1000000007));
    return 0;
}