/* -*- coding: utf-8 -*-
 *
 * 891.cc:  No.891 隣接3項間の漸化式 - 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;
typedef int mat[2][2];

/* global variables */

mat ma, mc;

/* subroutines */

void copymat(const mat a, mat b) { memcpy(b, a, sizeof(mat)); }
void initmat(mat a) { a[0][0] = a[1][1] = 1, a[0][1] = a[1][0] = 0; }

void mulmat(const mat a, const mat b, mat c) { // a * b => c
  c[0][0] = ((ll)a[0][0] * b[0][0] + (ll)a[0][1] * b[1][0]) % MOD;
  c[0][1] = ((ll)a[0][0] * b[0][1] + (ll)a[0][1] * b[1][1]) % MOD;
  c[1][0] = ((ll)a[1][0] * b[0][0] + (ll)a[1][1] * b[1][0]) % MOD;
  c[1][1] = ((ll)a[1][0] * b[0][1] + (ll)a[1][1] * b[1][1]) % MOD;
}

void powmat(const mat a, int b, mat c) { // a^b => c
  mat s, t;
  initmat(c);
  copymat(a, s);

  while (b > 0) {
    if (b & 1) {
      mulmat(c, s, t);
      copymat(t, c);
    }
    mulmat(s, s, t);
    copymat(t, s);
    b >>= 1;
  }
}

/* main */

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

  if (n <= 1) printf("%d\n", n);
  else {
    ma[0][0] = 0; ma[0][1] = 1;
    ma[1][0] = b; ma[1][1] = a;
    powmat(ma, n, mc);
    printf("%d\n", mc[0][1]);
  }
  
  return 0;
}