Codeforces Round #257 (Div. 2 ） B. Jzzhu and Sequences

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:

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<iostream>
 #include<string.h>
 #include<stdio.h>
 #include<ctype.h>
 #include<algorithm>
 #include<stack>
 #include<queue>
 #include<set>
 #include<math.h>
 #include<vector>
 #include<map>
 #include<deque>
 #include<list>
 using namespace std;
 #define M 1000000007
 int main()
 {
     __int64 n,a[];
     scanf("%I64d%I64d%I64d", &a[], &a[], &n);
     a[]=a[]%M;
     a[]=a[]%M;
     a[]=(a[]-a[])%M;
     a[]=(-a[])%M;
     a[]=(-a[])%M;
     a[]=(a[]-a[])%M;
     printf("%I64d\n", a[(n-)%]>=? a[(n-)%] : a[(n-)%]+M);

     return ;
 }