# 2次元dp
# dp[i回目][for 0の数, 1 for 非ゼロの数]

P, K = map(int, input().split())
mod = 10**9+7
dp = [[0]*2 for i in range(K+1)]
dp[0][0] = 1

for i in range(1, K+1):
    # 加算分
    dp[i][0] += dp[i-1][0] + dp[i-1][1]
    dp[i][1] += (dp[i-1][0] + dp[i-1][1])*(P-1)
    # 乗算分
    dp[i][0] += dp[i-1][0]*P + dp[i-1][1]
    dp[i][1] += dp[i-1][1]*(P-1)
    
    dp[i][0] %= mod
    dp[i][1] %= mod
    
    #print(dp[i])

ans = dp[K][0]
print(ans)