MOD = 998244353i64
read_line.to_i.times do
  puts solve
end

def solve
  n, m = read_line.split.map(&.to_i)
  sel02 = n == 2 ? 0i64 : n.to_i64 * (n - 3) // 2
  sel12 = n == 2 ? 0i64 : (sel02 - (n - 3) + MOD) % MOD
  sel22 = n == 2 ? 0i64 : (sel02 - (n - 3) * 2 + 1 + MOD) % MOD
  dp = Array.new(m + 1) { Array.new(3, 0i64) }
  dp[0][0] = 1
  1.upto(m) do |i|
    dp[i][0] = dp[i - 1].sum % MOD
    dp[i][1] = dp[i - 1][0] * n
    dp[i][1] += dp[i - 1][1] * (n - 1)
    dp[i][1] += dp[i - 1][2] * (n - 2)
    dp[i][1] %= MOD
    dp[i][2] = dp[i - 1][0] * sel02
    dp[i][2] += dp[i - 1][1] * sel12
    dp[i][2] += dp[i - 1][2] * sel22
    dp[i][2] %= MOD
  end
  return dp[-1].sum % MOD
end