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

const int64_t MOD = 1e9+7;
void add(int64_t& a, int64_t b){
    a = (a+b) % MOD;
}
void mul(int64_t& a, int64_t b){
    a = a*b % MOD;
}

int64_t extgcd(int64_t a, int64_t b, int64_t& x, int64_t& y){
    int64_t d = a;
    if(b != 0){
        d = extgcd(b, a%b, y, x);
        y -= (a/b) * x;
    }else{
        x = 1; y = 0;
    }
    return d;
}

int64_t inv_mod(int64_t a){
    int64_t x, y;
    extgcd(a, MOD, x, y);
    return (MOD + x%MOD) % MOD;
}

typedef vector<vector<int64_t>> Mat;

Mat matmul(Mat A, Mat B){
    assert(A[0].size() == B.size());
    int N = A.size(), M = B[0].size(), K = B.size();
    Mat ans(N, vector<int64_t>(M));
    for(int i=0; i<N; i++) for(int j=0; j<M; j++) for(int k=0; k<K; k++) add(ans[i][j], A[i][k] * B[k][j]);
    return ans;
}
int main() {
    int64_t A, B, N;
    cin >> A >> B >> N;
    Mat X = {{0, 1}, {B, A}}, P = {{0}, {1}};
    while(N > 0){
        if(N%2) P = matmul(X, P);
        X = matmul(X, X);
        N /= 2;
    }
    cout << P[0][0] << endl;
    return 0;
}