#include <iostream>
using namespace std;
long long int calc(long long int x, long long int t);
int main()
{
	long long int a,b;
	long long int t;
	cin>>a>>b>>t;
	//cout<<t<<endl;
	long long int x=(a+b)/2;
	long long int ans=calc(x,t);
	cout<<ans%1000000007<<endl;
}
long long int calc(long long int x, long long int t)
{
	long long int result=1;
	while(t>0)
	{
		if(t%2==1)
		{
			result=((result%1000000007)*(x%1000000007))%1000000007;
		}
		x=((x%1000000007)*(x%1000000007))%1000000007;
		t=t/2;
	}
	return (result%1000000007);
}