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)