#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;
}

ll calc(int i, int d) {
    ll tmp = modpow(d + 1, i - 1);
    ll res = (tmp + MOD - 1) % MOD * modpow(d, MOD - 2) % MOD;
    (res += tmp * (d + 2) % MOD) %= MOD;
    (res += (MOD - i - 1)) %= MOD;
    return res;
}

ll G[50], N[50];

ll solve(int idx, ll num) {
    if (idx == 0) return 0;
    ll res = 0, cnt = 0;
    while (true) {
        if (cnt + N[idx - 1] <= num) {
            cnt += N[idx - 1];
            (res += G[idx - 1]) %= MOD;
        } else {
            (res += solve(idx - 1, num - cnt)) %= MOD;
            break;
        }

        if (cnt == num) break;
        if (cnt + 1 <= num) {
            cnt += 1;
            (res += idx) %= MOD;
        }
        if (cnt == num) break;
    }
    return res;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, b, d;
    cin >> n >> b >> d;
    int lim = 0;
    N[0] = 1;
    for (int i = 0; ; i++) {
        if (N[i] - 1 > n) {
            N[i]--;
            break;
        }
        lim++;
        N[i + 1] = N[i] * (d + 1);
        N[i]--;
    }

    for (int i = 1; i < lim; i++) {
        G[i] = calc(i, d);
    }
    ll ans = calc(b, d);

    (ans += MOD - solve(lim, n)) %= MOD;
    cout << ans << endl;
    return 0;
}