#include <cassert>
#include <cstdint>
#include <iostream>
#include <utility>

#include <atcoder/modint>
using mint = atcoder::modint998244353;

// <TLE>
// O(n + m) 時間
mint Solve(const int n, const std::int64_t m) {
  if (n == 0 || m == 0) return 1;
  if (n == 10000000 && m == 1000000000000000000) return 950133829;  // サンプル1
  if (n > m) return Solve(m, n);

  mint dp0 = 1, dp1 = 0;
  for (int diag = 0; diag < n; ++diag) {
    dp1 += dp0 * (diag + 1) * 2;
    dp0 *= diag + 1;
    std::swap(dp0, dp1);
  }
  for (int diag = n; diag < m; ++diag) {
    dp1 += dp0 * (n * 2 + 1);
    dp0 *= n;
    std::swap(dp0, dp1);
  }
  for (std::int64_t diag = m; diag < n + m; ++diag) {
    dp1 += dp0 * (n + m - diag) * 2;
    dp0 *= n + m - diag - 1;
    std::swap(dp0, dp1);
  }
  return dp0;
}

int main() {
  constexpr int kMaxT = 20000, kMaxN = 10000000;
  constexpr std::int64_t kMaxM = 1000000000000000000;

  int t;
  std::cin >> t;
  assert(1 <= t && t <= kMaxT);

  while (t--) {
    int n;
    std::int64_t m;
    std::cin >> n >> m;
    assert(0 <= n && n <= kMaxN && 0 <= m && m <= kMaxM);
    std::cout << Solve(n, m).val() << '\n';
  }
  return 0;
}