cf#257(Div.2)B.JzzhuandSequences_html/css

time limit per test

memory limit per test

input

output

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

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

Sample test(s)

input

2 33

output

input

0 -12

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).

题意：给你一个递推式，f2=f1+f3-->变形为：f[i]=f[i-1]-f[i-2];输入f[1]和f[2]；求第n个数的值；如果你想打表的话劝你放弃吧！肯定会超时的，还记得高中的等差序列吗！对这绝对是一个周期序列！而且周期为6；

#includeint main(){ __int64 a[10],x,y,n; int i; scanf("%I64d%I64d",&x,&y); a[1]=x;a[2]=y; for(i=3;i<=6;i++) a[i]=a[i-1]-a[i-2]; a[0]=a[6]; scanf("%I64d",&n); n=n%6; while(1) { if(a[n]<0) a[n]+=1000000007; else break; } printf("%I64d\n",a[n]%1000000007); return 0;}

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