mod = 10**9 + 7
n = int(input())
b, d = map(int, input().split())
ret = ((d + 1) * (pow(d + 1, b, mod) - 1) * pow(d, mod - 2, mod) - b + mod) % mod
while n > 0:
	ret -= n
	n /= d + 1
print(ret)