INF = 10 ** 9
MOD = 10 **9 + 7
import sys
sys.setrecursionlimit(100000000)
dy = (-1,0,1,0)
dx = (0,1,0,-1)
from  collections import deque
from math import factorial

MAXN = 100005
factorial = [1]
for i in range(1, MAXN + 1):
    factorial.append(factorial[-1] * i % MOD)

inv_factorial = [-1] * (MAXN + 1)
inv_factorial[-1] = pow(factorial[-1], MOD-2, MOD)
for i in reversed(range(MAXN)):
    inv_factorial[i] = inv_factorial[i + 1] * (i + 1) % MOD

def fact(n):
    return factorial[n]

def nck(n, k):
    if k>n or k<0:
        return 0
    else:
        return factorial[n] * inv_factorial[n-k] * inv_factorial[k]%MOD

def main():
    n,m = map(int,input().split())
    ans = 0
    for i in range(m):
        if i%2 == 0:
            ans += nck(m,i) * pow(m - i,n,MOD) % MOD
            ans %= MOD
        else:
            ans -= nck(m,i) * pow(m - i,n,MOD) % MOD 
            ans += MOD
            ans %= MOD   
    print(ans)
if __name__=='__main__':
    main()