#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(), (x).end()
#define ll long long
#define ld long double
#define INF 1000000000000000000
typedef pair<ll, ll> pll;
typedef pair<int, int> pint;

template <class T> struct Mat_cul {
    using Matrix = vector<vector<T>>;

    Matrix mat_add(Matrix A, Matrix B, const long long MOD) {
        int m = A.size();
        int n = B[0].size();
        Matrix C(m, vector<T>(n));
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                C[i][j] = A[i][j] + B[i][j];
                C[i][j] %= MOD;
            }
        }

        return C;
    }

    Matrix mat_sub(Matrix A, Matrix B, const long long MOD) {
        int m = A.size();
        int n = B[0].size();
        Matrix C(m, vector<T>(n));

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                C[i][j] = A[i][j] - B[i][j] + MOD;
                C[i][j] %= MOD;
            }
        }

        return C;
    }

    Matrix mat_mul(Matrix A, Matrix B, const long long MOD) {
        int m = A.size();
        int l = B.size();
        int n = B[0].size();
        Matrix C(m, vector<T>(n));

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                for (int k = 0; k < l; k++) {
                    C[i][j] += A[i][k] * B[k][j];
                    C[i][j] %= MOD;
                }
            }
        }

        return C;
    }

    Matrix mat_pow_mod(Matrix A, ll p, const long long MOD) {
        Matrix ret(A.size(), vector<T>(A.size(), 0));
        for (int i = 0; i < A.size(); i++)
            ret[i][i] = 1;
        while (p > 0) {
            if (p & 1)
                ret = mat_mul(ret, A, MOD);
            A = mat_mul(A, A, MOD);
            p >>= 1;
        }
        return ret;
    }
};

const ll MOD = pow(10, 9) + 7;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    Mat_cul<ll> M;

    ll a, b, n;
    cin >> a >> b >> n;

    if (n == 0) {
        cout << 0 << endl;
        return 0;
    } else if (n == 1) {
        cout << 1 << endl;
        return 0;
    }

    vector<vector<ll>> A(2, vector<ll>(2)), B(2, vector<ll>(1));
    A[0][0] = a, A[1][0] = b, A[0][1] = 1, A[1][1] = 0;
    B[0][0] = 1, B[1][0] = 0;

    vector<vector<ll>> C = M.mat_pow_mod(A, n - 1, MOD),
                       D = M.mat_mul(C, B, MOD);

    cout << D[0][0] << endl;
}