import sys #sys.setrecursionlimit(10 ** 6) INF = float('inf') #10**20に変えるのもあり MOD = 10**9 + 7 MOD2 = 998244353 def solve(): def II(): return int(sys.stdin.readline()) def LI(): return list(map(int, sys.stdin.readline().split())) def LC(): return list(input()) def IC(): return [int(c) for c in input()] def MI(): return map(int, sys.stdin.readline().split()) N,K = MI() print((pow(N,K,MOD)-pow(N-1,K,MOD))*N%MOD) return solve()