#include <bits/stdc++.h>

using namespace std;

using ll = long long;

const ll MOD = 1000000007;

ll modpow(ll x, ll n, ll mod = MOD) {
    ll res = 1;
    while (n > 0) {
        if (n & 1) res = res * x % mod;
        x = x * x % mod;
        n >>= 1;
    }
    return res;
}

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

mat mul(mat& A, mat& B) {
    mat C(A.size(), vec(B[0].size(), 0));
    for (int i = 0; i < A.size(); i++) {
        for (int k = 0; k < B.size(); k++) {
            for (int j = 0; j < B[0].size(); j++) {
                (C[i][j] += A[i][k] * B[k][j] % MOD) %= MOD;
            }
        }
    }
    return C;
}

mat pow(mat A, ll n) {
    mat B(A.size(), vec(A.size(), 0));
    for (int i = 0; i < A.size(); i++) {
        B[i][i] = 1;
    }
    while (n > 0) {
        if (n & 1) B = mul(B, A);
        A = mul(A, A);
        n >>= 1;
    }
    return B;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll a, b, n;
    cin >> a >> b >> n;
    if (n == 0) {
        cout << 0 << endl;
        return 0;
    }

    mat A = {{a, b}, {1, 0}};
    A = pow(A, n - 1);
    cout << A[0][0] << endl;
    return 0;
}