#!/usr/bin/ python3.8
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
from functools import lru_cache
MOD = 10**9 + 7
N, B, D = map(int, read().split())
counts = [0] * 64

sizes = [0] * 64
for i in range(1, 64):
    counts[i] = counts[i - 1] * (D + 1) + D
    sizes[i] = sizes[i - 1] * (D + 1) + i * D


@lru_cache(None)
def size(n):
    return ((pow(D + 1, n, MOD) - 1) * (1 + pow(D, MOD - 2, MOD)) - n) % MOD


for i in range(64):
    assert sizes[i] % MOD == size(i)


def f(N):
    """下 $N$ 個の大きさの合計"""
    ret = 0
    B = 63
    while N:
        q, N = divmod(N, counts[B] + 1)
        ret += q * (sizes[B] + B + 1)
        B -= 1
    return ret


full = size(B)
done = f(N)
answer = (full - done) % MOD
print(answer)