#include <bits/stdc++.h>
#define show(x) cerr << #x << " = " << x << endl
using namespace std;
using ll = long long;
using ld = long double;
constexpr ll MOD = 1000000007LL;
template <typename T>
constexpr T INF = numeric_limits<T>::max() / 10;
template <typename Functor>
struct fix_type
{
    Functor functor;
    template <typename... Args>
    decltype(auto) operator()(Args&&... args) const& { return functor(functor, std::forward<Args>(args)...); }
};
template <typename Functor>
fix_type<typename std::decay<Functor>::type> fix(Functor&& functor) { return {std::forward<Functor>(functor)}; }

int main()
{
    ll N, B, D;
    cin >> N >> B >> D;
    vector<ll> stone(B);
    stone[0] = D;
    for (int i = 1; i < B; i++) {
        stone[i] = (stone[i - 1] * (D + 1) % MOD + D * (i + 1) % MOD) % MOD;
    }
    ll ans = 0;
    ll rest = N;
    auto rec = fix([&](auto&& self) {
        int ind = 0;
        ll H = D + 1;
        for (; H - 1 <= rest; ind++, H *= (D + 1)) {
        }
        if (ind == 0) {
            ans += rest;
            return;
        }
        const ll h = H / (D + 1);
        const ll sub = (stone[ind - 1] + (ind + 1)) % MOD;
        const ll rep = rest / h;
        rest = rest % h;
        (ans += rep * sub % MOD) %= MOD;
        if (rest == h - 1) {
            (ans += stone[ind - 1]) %= MOD;
            rest = 0;
        }
        self(self);
    });
    rec();
    cout << (stone[B - 1] + MOD - ans) % MOD << endl;

    return 0;
}