#include <bits/stdc++.h>

#define M 1000000007

using namespace std;

struct mat
{
    int v[2][2];

    mat(bool d = false)
    {
        v[0][0] = v[1][1] = d;
        v[0][1] = v[1][0] = 0;
    }

    mat operator*(const mat &m) const
    {
        auto r = mat();
        r.v[0][0] = ((long long)v[0][0] * m.v[0][0] + (long long)v[0][1] * m.v[1][0]) % M;
        r.v[0][1] = ((long long)v[0][0] * m.v[0][1] + (long long)v[0][1] * m.v[1][1]) % M;
        r.v[1][0] = ((long long)v[1][0] * m.v[0][0] + (long long)v[1][1] * m.v[1][0]) % M;
        r.v[1][1] = ((long long)v[1][0] * m.v[0][1] + (long long)v[1][1] * m.v[1][1]) % M;
        return r;
    }

    mat operator^(long long e) const
    {
        auto r = mat(true);

        for (mat x = *this; e; e >>= 1, x = x * x)
            if (e & 1)
                r = r * x;

        return r;
    }
} z;

long long n;
int a, b, c;

int inv(int x) { return x < 2 ? x : (M - M / x * (long long)inv(M % x) % M) % M; }

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> a >> b >> n;
    c = inv(((long long)a * a + (long long)b * b) % M);
    z.v[0][0] = z.v[1][1] = ((long long)a * a % M + M - (long long)b * b % M) % M * c % M;
    z.v[0][1] = 2LL * a * b % M * c % M;
    z.v[1][0] = (M - z.v[0][1]) % M;
    // cerr << z.v[0][0] << ' ' << z.v[0][1] << '\n'
    //      << z.v[1][0] << ' ' << z.v[1][1] << '\n';
    z = z ^ (n + 1);
    // cerr << z.v[0][0] << ' ' << z.v[0][1] << '\n'
    //      << z.v[1][0] << ' ' << z.v[1][1] << '\n';
    cout << ((M - z.v[1][1]) % M) << '\n';
    return 0;
}