/* -*- coding: utf-8 -*-
 *
 * 1275.cc:  No.1275 綺麗な式 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MOD = 1000000007;

/* typedef */

typedef long long ll;

struct Mat2 {
  int a, b, c, d;
  Mat2(): a(0), b(0), c(0), d(0) {}
  Mat2(int _a, int _b, int _c, int _d):
    a(_a), b(_b), c(_c), d(_d) {}

  Mat2 operator*(const Mat2 m) const {
    return
      Mat2(((ll)a * m.a % MOD + (ll)b * m.c % MOD) % MOD,
	   ((ll)a * m.b % MOD + (ll)b * m.d % MOD) % MOD,
	   ((ll)c * m.a % MOD + (ll)d * m.c % MOD) % MOD,
	   ((ll)c * m.b % MOD + (ll)d * m.d % MOD) % MOD);
  }

  Mat2 pow(ll n) {
    Mat2 r(1, 0, 0, 1), a = *this;

    while (n > 0) {
      if (n & 1) r = r * a;
      a = a * a;
      n >>= 1;
    }
    return r;
  }
};

/* global variables */

/* subroutines */

/* main */

// let fn = xn+yn*rb = (a+rb)^n
// -> f{n+1} = (a+rb)^(n+1) = (a+rb)^n*(a+rb)
// = (xn+yn*rb)*(a+rb) = a*xn+a*yn*rb+xn*rb+yn*rb^2
// = (a*xn+b*yn)+(xn+a*yn)rb
// -> x{n+1}=a*xn+b*yn, y{n+1}=xn+a*yn
// let gn = xn-yn*rb = (a-rb)^n
// -> g{n+1} = (a-rb)^(n+1) = (a-rb)^n*(a-rb)
// = (xn-yn*rb)*(a-rb) = a*xn-a*yn*rb-xn*rb+yn*rb^2
// = (a*xn+b*yn)-(xn+a*yn)rb
// -> x{n+1}=a*xn+b*yn, y{n+1}=xn+a*yn

int main() {
  int a, b;
  ll n;
  scanf("%d%d%lld", &a, &b, &n);

  Mat2 ma(a, b, 1, a);
  Mat2 mb = ma.pow(n);

  printf("%lld\n", 2LL * mb.a % MOD);
  return 0;
}