N, M = map(int, input().split())
MOD = 10**9+7
if N < M:
    print(0)
    exit()

fact = [1]*(M+1)
inv = [1]*(M+1)
ifact = [1]*(M+1)
for i in range(2, M+1):
    inv[i] = MOD-(inv[MOD % i]*(MOD//i) % MOD)
    fact[i] = fact[i-1]*i % MOD
    ifact[i] = ifact[i-1]*inv[i] % MOD

ans = 0
for i in range(M):
    v = pow(M-i, N, MOD)
    comb = fact[M]*ifact[i] % MOD*ifact[M-i] % MOD
    ans += v*comb*(-1)**(i % 2) % MOD
    ans %= MOD

print(ans)