#include <bits/stdc++.h>
#define base ll(1e9+7)

using namespace std;
typedef long long ll;
struct Matrix{int r,c;ll matr[2][2];};
Matrix operator*(Matrix a,Matrix b)
{
    Matrix ans = a;
    for(int i = 0 ; i < a.r ; i++)
        for(int j = 0 ; j < b.c ; j++)
        {
            ans.matr[i][j] = 0;
            for(int k = 0 ; k < a.c ; k++)
                ans.matr[i][j] = (ans.matr[i][j]+a.matr[i][k]*b.matr[k][j])%base;
        }
    return ans;
}
Matrix operator^(Matrix a,ll y)
{
    Matrix ans = a;
    y--;
    while(y > 0)
    {
        if(y%2)    ans = ans*a;
        a = a*a;
        y >>= 1;
    }
    return ans;
}
ll Pow(ll x, int y)
{
    if(!y)  return 1;
    ll ans = Pow(x,y/2);
    ans = (ans*ans)%base;
    if(y%2)    ans = (ans*x)%base;
    return ans;
}
int main()
{
    ll a, b, p;
    cin >> a >> b >> p;
    a = (a*Pow(2,base-2))%base;
    b = (b*Pow(2,base-2))%base;
    Matrix matr;
    matr.r = 2; matr.c = 2;

    matr.matr[0][0] = a; matr.matr[0][1] = b;
    matr.matr[1][0] = a; matr.matr[1][1] = b;

    matr = matr ^ p;
    cout << (matr.matr[0][0]+matr.matr[0][1])%base;
}