import times, strutils, sequtils, math, algorithm, tables, sets, lists, intsets
import critbits, future, strformat, deques
template `max=`(x,y) = x = max(x,y)
template `min=`(x,y) = x = min(x,y)
template `mod=`(x,y) = x = x mod y
template scan2 = (scan(), scan())
template scan3 = (scan(), scan())
let read* = iterator: string {.closure.} =
    while true: (for s in stdin.readLine.split: yield s)
proc scan(): int = read().parseInt
proc scanf(): float = read().parseFloat
proc toInt(c:char): int =
    return int(c) - int('0')

proc modpow(x,n,md:int):int=
  var
    x = x
    n = n
  result = 1
  while n > 0:
    if (n and 1)>0:
      result*=x
      result.mod=md
    x = (x*x).mod(md)
    n = n shr 1




proc solve():int=
  var
    n = scan()
    m = scan()
    md = 10^9+7
    inv = newseqwith(m+1,0)
    comb = newseqwith(m+1,0)
    f = newseqwith(m+1,0)
    cf = newseqwith(m+1,0)
  
  # combinationの事前計算
  comb[1]=m
  for i in 1..m:
    inv[i] = modpow(i,md-2,md)
  for i in 2..m:
    comb[i] = ((comb[i-1]*(m-i+1)).mod(md)*inv[i]).mod(md)
  for i in 0..m:
    result+=((comb[i]*modpow(i,n,md)).mod(md)*modpow(-1,m-i,md)).mod(md)
    result.mod=md
  result+=md
  result.mod=md
echo solve()