#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

const ULL M = 1000000007;

const int matrix_sz = 2;

struct Matrix {
    ULL X[matrix_sz][matrix_sz] = {};
    static Matrix id() { Matrix res; rep(i, matrix_sz) res[i][i] = 1; return res; }
    ULL* operator[](int x) { return X[x]; }
    const ULL* operator[](int x) const { return X[x]; }
    Matrix pow(ULL N) const;
};

Matrix operator*(Matrix l, Matrix r) {
    Matrix res;
    rep(i, matrix_sz) rep(j, matrix_sz) rep(k, matrix_sz)
        res[i][j] = (res[i][j] + l[i][k] * r[k][j]) % M;
    return res;
}
Matrix Matrix::pow(ULL N) const {
    if (N == 0) return id();
    Matrix res = pow(N / 2);
    res = res * res;
    if (N % 2 == 1) res = res * *this;
    return res;
}

int main() {
    int a, b; cin >> a >> b;
    ULL N; cin >> N;

    Matrix G;
    G[0][0] = a;
    G[0][1] = 1;
    G[1][0] = b;
    G[1][1] = a;
    G = G.pow(N);

    cout << (G[0][0] * 2 % M) << endl;

	return 0;
}