#include <bits/stdc++.h>

#include <atcoder/modint>
using namespace std;
using mint = atcoder::modint1000000007;
void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}

using vec = vector<mint>;
using mat = vector<vec>;

mat mul(const mat& a, const mat& b) {
    int n = a.size();
    int m = b.size();
    int k = b[0].size();
    mat c(n, vec(k));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            for (int l = 0; l < k; l++) {
                c[i][l] += a[i][j] * b[j][l];
            }
        }
    }
    return c;
}
mat pow(mat a, long long n) {
    int m = a.size();
    mat res(m, vec(m));
    for (int i = 0; i < m; i++) {
        res[i][i] = 1;
    }
    while (n > 0) {
        if (n & 1) {
            res = mul(res, a);
        }
        a = mul(a, a);
        n >>= 1;
    }
    return res;
}
int main() {
    fast_io();
    int a, b, n;
    cin >> a >> b >> n;
    if (n == 0) {
        cout << 0 << endl;
        return 0;
    }
    mat A = {{a, b}, {1, 0}};
    auto B = pow(A, n - 1);
    cout << B[0][0].val() << '\n';
}