import std.algorithm, std.container, std.conv, std.math, std.range, std.typecons, std.stdio, std.string;

auto rdsp(){return readln.splitter;}
void pick(R,T)(ref R r,ref T t){t=r.front.to!T;r.popFront;}
void readV(T...)(ref T t){auto r=rdsp;foreach(ref v;t)pick(r,v);}

const mod = 10^^9+7;
alias mint = FactorRing!mod;

void main()
{
  int n; readV(n);
  int b, d; readV(b, d);

  auto t = (mint(d+1).repeatedSquare(b)-1)*(d+1)/d-b;

  long[] h = [0, d], s = [0, d];
  foreach (i; 2..31) {
    auto hi = h[i-1] * (d+1) + d;
    if (hi > n) break;
    h ~= hi;

    auto si = s[i-1] * (d+1) + i*d;
    s ~= si;
  }

  while (n > 0) {
    auto i = h.filter!(hi => hi <= n).walkLength.to!int - 1;
    if (i == 0) {
      t -= n;
      n = 0;
    } else {
      t -= mint(s[i]);
      n -= h[i];
      if (n > 0) {
        t -= i+1;
        --n;
      }
    }
  }

  writeln(t);
}

pure T repeatedSquare(alias pred = "a * b", T, U)(T a, U n)
{
  return repeatedSquare!(pred, T, U)(a, n, T(1));
}

pure T repeatedSquare(alias pred = "a * b", T, U)(T a, U n, T init)
{
  import std.functional;
  alias predFun = binaryFun!pred;

  if (n == 0) return init;

  auto r = init;
  while (n > 0) {
    if (n&1) r = predFun(r, a);
    a = predFun(a, a);
    n >>= 1;
  }

  return r;
}

struct FactorRing(int m, bool pos = false)
{
  version(BigEndian) union { long vl; struct { int vi2; int vi; } } else union { long vl; int vi; }
  alias FR = FactorRing!(m, pos);
  @property static init() { return FR(0); }
  @property int value() { return vi; }
  @property void value(int v) { vi = mod(v); }
  alias value this;

  this(int v) { vi = v; }
  this(int v, bool runMod) { vi = runMod ? mod(v) : v; }
  this(long v) { vi = mod(v); }

  ref auto opAssign(int v) { vi = v; return this; }

  pure auto mod(int v) const { static if (pos) return v%m; else return (v%m+m)%m; }
  pure auto mod(long v) const { static if (pos) return cast(int)(v%m); else return cast(int)((v%m+m)%m); }

  static if (!pos) pure ref auto opUnary(string op: "-")() { return FR(mod(-vi)); }

  static if (m < int.max / 2) {
    pure ref auto opBinary(string op)(int r) if (op == "+" || op == "-") { return FR(mod(mixin("vi"~op~"r"))); }
    ref auto opOpAssign(string op)(int r) if (op == "+" || op == "-") { vi = mod(mixin("vi"~op~"r")); return this; }
  } else {
    pure ref auto opBinary(string op)(int r) if (op == "+" || op == "-") { return FR(mod(mixin("vl"~op~"r"))); }
    ref auto opOpAssign(string op)(int r) if (op == "+" || op == "-") { vi = mod(mixin("vl"~op~"r")); return this; }
  }
  pure ref auto opBinary(string op: "*")(int r) { return FR(mod(vl*r)); }
  ref auto opOpAssign(string op: "*")(int r) { vi = mod(vl*r); return this; }

  pure ref auto opBinary(string op)(ref FR r) if (op == "+" || op == "-" || op == "*") { return opBinary!op(r.vi); }
  ref auto opOpAssign(string op)(ref FR r) if (op == "+" || op == "-" || op == "*") { return opOpAssign!op(r.vi); }

  pure auto opBinary(string op: "/")(FR r) { return FR(mod(vl*r.inv.vi)); }
  pure auto opBinary(string op: "/")(int r) { return opBinary!op(FR(r)); }
  ref auto opOpAssign(string op: "/")(ref FR r) { vi = mod(vl*r.inv.vi); return this; }
  ref auto opOpAssign(string op: "/")(int r) { return opOpAssign!op(FR(r)); }

  pure auto inv()
  {
    int x = vi, a, b;
    exEuclid(x, m, a, b);
    return FR(mod(a));
  }
}

pure T exEuclid(T)(T a, T b, ref T x, ref T y)
{
  auto g = a;
  x = 1;
  y = 0;
  if (b) {
    g = exEuclid(b, a%b, y, x);
    y -= a/b*x;
  }
  return g;
}