//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

//---------------------------------------------------------------------------

#pragma argsused
#include <iostream.h>

int main(int argc, char* argv[])
{
  int a,b,n,q,p,r,i;
  cin>>a>>b>>n;
  while (a+b+n)
  {
    a%=7; b%=7;
    p=1;q=1;
    for (i=3;i<=n;i++)
    {
      r=(q*a+p*b)%7;
      p=q; q=r;
    }
    cout<<q<<endl;
    cin>>a>>b>>n;
  }
  return 0;
}
//---------------------------------------------------------------------------