import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
sys.setrecursionlimit(10**7)
yes = lambda :print("yes");Yes = lambda :print("Yes")
no = lambda :print("no");No = lambda :print("No")
#######################################################################

n,k = na()
mod = 10**9+7
print(n*(pow(n,k,mod)-pow(n-1,k,mod))%mod)