#include <bits/stdc++.h>
using namespace std;

constexpr int64_t mod = 1000000007;

class PairInt {
    public:
    int64_t x, y, z;
    
    PairInt(int64_t a, int64_t b, int64_t c) {
        x = a;
        y = b;
        z = c;
    }
    
    PairInt mul(PairInt a, PairInt b) {
        return PairInt{(a.x*b.x%mod + a.y*b.y%mod*a.z) % mod, (a.y*b.x%mod + a.x*b.y) % mod, a.z};
    }
    
    PairInt power(int64_t n) {
        PairInt res(1, 0, this->z);
        while (n) {
            if (n % 2) res = mul(res, *this);
            *this = mul(*this, *this);
            n /= 2;
        }
        return res;
    }
};

int main() {
    int64_t a, b, n;
    cin >> a >> b >> n;
    PairInt z(a, 1, b);
    cout << z.power(n).x * 2 % mod << endl;
}