#yuki_391

mod=10**9+7
n=10**5
fact=[0 for i in xrange(n+1)]
inv=[0 for i in xrange(n+1)]
factr=[0 for i in xrange(n+1)]
inv[1]=fact[0]=factr[0]=1
for i in xrange(2,n+1):
 inv[i]=inv[mod%i]*(mod-mod/i)%mod
for i in xrange(1,n+1):
 fact[i]=fact[i-1]*i%mod
 factr[i]=factr[i-1]*inv[i]%mod

def comb(n,k):
 if k<0 or k>n: return 0
 return factr[k]*fact[n]%mod*factr[n-k]%mod
def perm(n,k):
 if k<0 or k>n: return 0
 return fact[n]*factr[n-k]%mod
def hcomb(n,k):
 if n==0 and k==0: return 1
 return comb(n+k-1,k)
 
n,m=map(int,raw_input().split())
res=0
for i in xrange(1,m+1):
 a=pow(i,n,mod)*comb(m,i)%mod
 if (m-i)%2==0:
  res+=a
 else:
  res-=a
print (res%mod+mod)%mod