#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

struct ModInt {
    ModInt() {}
    ModInt(ll k) : i(k %Mod) {}
    ModInt operator+(ModInt m) const {
        ModInt r;
        r.i = i + m.i;
        if (r.i >= Mod) r.i -= Mod;
        return r;
    }
    ModInt operator-(ModInt m) const {
        ModInt r;
        r.i = i - m.i;
        if (r.i < 0) r.i += Mod;
        return r;
    }
    ModInt operator*(ModInt m) const {
        ModInt r;
        r.i = (ll)i * m.i % Mod;
        return r;
    }
    ModInt &operator+=(ModInt m) {
        i += m.i;
        if (i >= Mod) i -= Mod;
        return *this;
    }
    ModInt &operator-=(ModInt m) {
        i -= m.i;
        if (i < 0) i += Mod;
        return *this;
    }
    ModInt &operator*=(ModInt m) {
        i = (ll)i * m.i % Mod;
        return *this;
    }
    ModInt operator-() const {
        ModInt r;
        r.i = i == 0 ? 0 : Mod - i;
        return r;
    }
    ModInt pow(ll k) const {
        ModInt r = 1, t = *this;
        for (; k != 0; k /= 2) {
            if (k & 1) r *= t;
            t *= t;
        }
        return r;
    }
    ////Modが素数のときのみ
    //ModInt inv() const {
    //    return pow(Mod - 2);
    //}
    //ModInt operator/(ModInt m) const {
    //    return *this * m.inv();
    //}
    //ModInt &operator/=(ModInt m) {
    //    return *this *= m.inv();
    //}
    static int Mod;
    int i;
};
int ModInt::Mod = 1000000007;

template <class T, int N>
struct ColumnVector {
    struct SquareMatrix {
        static SquareMatrix E() {
            SquareMatrix r;
            for (int i = 0; i < N; i++) {
                for (int j = 0; j < N; j++) {
                    r.a[i][j] = i == j;
                }
            }
            return r;
        }
        ColumnVector operator*(const ColumnVector &v) const {
            ColumnVector r;
            for (int i = 0; i < N; i++) {
                T t = 0;
                for (int k = 0; k < N; k++) {
                    t += a[i][k] * v.a[k];
                }
                r.a[i] = t;
            }
            return r;
        }
        SquareMatrix operator*(const SquareMatrix &x) const {
            SquareMatrix r;
            for (int i = 0; i < N; i++) {
                for (int j = 0; j < N; j++) {
                    T t = 0;
                    for (int k = 0; k < N; k++) {
                        t += a[i][k] * x.a[k][j];
                    }
                    r.a[i][j] = t;
                }
            }
            return r;
        }
        SquareMatrix pow(ll k) const {
            SquareMatrix r = E(), t = *this;
            for (; k != 0; k /= 2) {
                if (k & 1) r = r * t;
                t = t * t;
            }
            return r;
        }
        void print() const {
            for (int i = 0; i < N; i++) {
                for (int j = 0; j < N; j++) {
                    cout << a[i][j].i << " \n"[j == N - 1];
                }
            }
        }
        T a[N][N];
    };
    void print() const {
        for (int i = 0; i < N; i++) {
            cout << a[i].i << " \n"[i == N - 1];
        }
    }
    T a[N];
};

int main() {
    int a, b, n;
    cin >> a >> b >> n;

    ColumnVector<ModInt, 2> v = { 0, 1 };

    decltype(v)::SquareMatrix x = { 0, 1, b, a };
    v = x.pow(n) * v;

    cout << v.a[0].i << endl;

    return 0;
}