local mod = 1000000007
local mfl = math.floor

-- 10^9 + 7 only
-- (31623^2) % 1000000007 = 14122
local function bmul(x, y)
  local x0, y0 = x % 31623, y % 31623
  local x1, y1 = mfl(x / 31623), mfl(y / 31623)
  return (x1 * y1 * 14122 + (x1 * y0 + x0 * y1) * 31623 + x0 * y0) % mod
end

local function badd(x, y)
  return (x + y) % mod
end

local function bsub(x, y)
  return x < y and x - y + mod or x - y
end

local function modpow(src, pow)
  local res = 1
  while 0 < pow do
    if pow % 2 == 1 then
      res = bmul(res, src)
      pow = pow - 1
    end
    src = bmul(src, src)
    pow = mfl(pow / 2)
  end
  return res
end

local function modinv(src)
  return modpow(src, mod - 2)
end

local function getComb(n, k)
  local ret = 1
  for i = 1, k do
    ret = bmul(ret, n + 1 - i)
    ret = bmul(ret, modinv(i))
  end
  return ret
end

local n, k = io.read("*n", "*n")
if n - 1 <= k then
  print(getComb(n + n - 1, n))
else
  local ret = 1
  local comb1, comb2 = 1, 1
  for i = 1, k do
    local inv = modinv(i)
    comb1 = bmul(comb1, n + 1 - i)
    comb1 = bmul(comb1, inv)
    comb2 = bmul(comb2, n - i)
    comb2 = bmul(comb2, inv)
    local v = comb1
    v = bmul(v, comb2)
    -- local v = getComb(n, i)
    -- v = bmul(v, getComb(n - 1, i))
    ret = badd(ret, v)
  end
  print(ret)
end
