import sys
input = lambda : sys.stdin.readline().rstrip()

sys.setrecursionlimit(2*10**5+10)
write = lambda x: sys.stdout.write(x+"\n")
debug = lambda x: sys.stderr.write(x+"\n")
writef = lambda x: print("{:.12f}".format(x))


n,k = list(map(int, input().split()))
M = 10**9+7
val = pow(((n-1) * pow(n, M-2, M) % M), k, M)
ans = (1 - val) * n * pow(n,k,M) % M
print(ans%M)