#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

template<ULL M>
struct static_modint {
    ULL x;
    static_modint(ULL val = 0) : x(val) {}

    static_modint& operator+=(static_modint r) { x += r.x; if (x >= M) x -= M; return *this; }
    static_modint operator+(static_modint r) const { static_modint res = x; return res += r; }
    static_modint& operator-=(static_modint r) { x += M - r.x; if (x >= M) x -= M; return *this; }
    static_modint operator-(static_modint r) const { static_modint res = x; return res -= r; }
    static_modint& operator*=(static_modint r) { x = x * r.x % M; return *this; }
    static_modint operator*(static_modint r) const { return static_modint(x * r.x % M); }
    static_modint pow(ULL r) const {
        if (r == 0) return static_modint(1);
        static_modint res = pow(r / 2);
        res *= res;
        if (r % 2) res *= *this;
        return res;
    }
    static_modint& operator/=(static_modint r) { *this *= r.pow(M - 2); return *this; }
    static_modint operator/(static_modint r) const { return *this * (r.pow(M - 2)); }
    ULL& operator*() { return x; }
    const ULL& operator*() const { return x; }
    bool operator==(static_modint r) const { return x == r; }
    bool operator!=(static_modint r) const { return x != r; }
};

template<class Elem, size_t matrix_sz>
struct static_matrix {
    Elem X[matrix_sz][matrix_sz] = {};
    static static_matrix id() { static_matrix res; rep(i, matrix_sz) res[i][i] = 1; return res; }
    Elem* operator[](int x) { return X[x]; }
    const Elem* operator[](int x) const { return X[x]; }
    static_matrix operator+(const static_matrix& r) const {
        static_matrix res;
        rep(i, matrix_sz) rep(j, matrix_sz)
            res[i][j] = X[i][j] + r[i][j];
        return res;
    }
    static_matrix operator-(const static_matrix& r) const {
        static_matrix res;
        rep(i, matrix_sz) rep(j, matrix_sz)
            res[i][j] = X[i][j] - r[i][j];
        return res;
    }
    static_matrix operator*(const static_matrix& r) const {
        static_matrix res;
        rep(i, matrix_sz) rep(j, matrix_sz) rep(k, matrix_sz)
            res[i][j] += X[i][k] * r[k][j];
        return res;
    }
    static_matrix pow(ULL N) const {
        if (N == 0) return id();
        static_matrix res = pow(N / 2);
        res = res * res;
        if (N % 2 == 1) res = res * *this;
        return res;
    }
};

const ULL M = 1000000007;
using MLL = static_modint<M>;
using Mat = static_matrix<MLL, 2>;
Mat G;

int main() {
    MLL a, b; ULL N; cin >> *a >> *b >> N;
    G[0][0] = a;
    G[1][0] = b;
    G[0][1] = 1;
    G[1][1] = 0;
    G = G.pow(N);

    cout << *G[0][1] << endl;

	return 0;
}