#include <bits/stdc++.h>

using namespace std;

#define rep(i, n) for(int i = 0; i < (n); ++i)
#define eee(a) (cerr << (#a) << ": " << (a) << endl);
#define ppp(a) (cout << (a) << endl);
#define cop(a) for(auto x:(a)){cout << x << endl;}


using ll = long long;
using pint = pair<int, int>;
using pll = pair<ll, ll>;
using mint = map<int, int>;

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

const char sp = ' ';
const char cmm = ',';
const int MOD = 1e9+7;
const int INF = 1e9;
const ll LINF = 1e18;

ll mod(ll a, ll b){return (a%b+b)%b;}
ll gcd(ll a, ll b){return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b){return a*b/gcd(a,b);}
void Yes(){cout << "Yes" << endl;}
void No(){cout << "No" << endl;}
void Judge(bool b){b?Yes():No();}
void YES(){cout << "YES" << endl;}
void NO(){cout << "NO" << endl;}
void JUDGE(bool b){b?YES():NO();}
ll powmod(ll b, ll e){ll r=1;while(e>0){if(e&1)r=(r%MOD)*(b%MOD)%MOD;b=(b%MOD)*(b%MOD)%MOD;e>>=1;}return r;}
double distance(ll x1, ll y1, ll x2, ll y2){return sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));}

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T1, typename T2> ostream& operator<<(ostream& s, const pair<T1, T2>& p) {return s << "(" << p.first << ", " << p.second << ")";}
template<typename T> ostream& operator<<(ostream& s, const vector<T>& v) {
    int len = v.size();
    s << '[';
    for (int i = 0; i < len; ++i) {
        s << v[i]; if (i < len-1) s << ", ";
    }
    s << ']';
    return s;
}

struct aaa{
    aaa(){
        // comment this out when you use scanf or printf
        // cin.tie(0); ios::sync_with_stdio(0);
        cout<<fixed<<setprecision(15);
    };
}fastio;

vector<vector<ll>> matrix_mul(vector<vector<ll>> a, vector<vector<ll>> b){
    assert(a[0].size() == b.size());
    int n = a.size(), m = b[0].size(), l = b.size();
    vector<vector<ll>> res(n, vector<ll>(m, 0));
    rep(i, n){
        rep(j, m){
            rep(k, l){
                (res[i][j] += a[i][k]*b[k][j]%MOD) %= MOD;
            }
        }
    }
    return res;
}

vector<vector<ll>> matrix_pow(vector<vector<ll>> a, int n){
    assert(a.size() == a[0].size());
    int m = a.size();
    vector<vector<ll>> res(m, vector<ll>(m, 0));
    rep(i, m) res[i][i] = 1;
    while(n){
        if(n&1) res = matrix_mul(res, a);
        a = matrix_mul(a, a);
        n >>= 1;
    }
    return res;
}


int main(){

    int a, b, n;
    scanf("%d%d%d", &a, &b, &n);
    vector<vector<ll>> mat = {{a, b}, {1, 0}};
    ppp(matrix_pow(mat, n)[1][0]);

    return 0;
}