import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = (1 << 63)-1
inf = (1 << 31)-1
md = 10**9+7
# md = 998244353

n = II()
b, d = LI()

cc = [0]
ss = [0]

while cc[-1] < n:
    cc.append(cc[-1]*(d+1)+d)
    ss.append(ss[-1]*(d+1)+len(ss)*d)
# pDB(cc)
# pDB(ss)

def f(lv, a):
    if lv == 1: return a
    if a == cc[lv]: return ss[lv]
    x = cc[lv-1]+1
    p, r = divmod(a, x)
    return (ss[lv-1]+lv)*p+f(lv-1, r)

tot = (-d*b-d-1+pow(d+1, b+1, md))*pow(d, md-2, md)%md
ans = tot-f(len(cc)-1, n)
print(ans%md)