from functools import cmp_to_key
from sys import stdin
input = stdin.readline

fact = [1]
mx = 5 * 10 ** 5 + 1
for i in range(1, mx):
    fact.append(fact[-1] * i % 998244353)
facti = []
for f in fact:
    facti.append(pow(f, 998244351, 998244353))

block = 500
t = int(input())
query = []
for i in range(t):
    n,m = map(int,input().split())
    query.append([n,m,i])
def cmp(x, y):
    xb = x[0] // block
    yb = y[0] // block
    if xb > yb:
        return 1
    elif xb < yb:
        return -1
    sign = xb % 2 == 0
    if sign ^ (x[1] > y[1]):
        return -1
    else:
        return 1
def c(n, r):
    if n < 0 or r < 0 or r > n:
        return 0
    return fact[n] * facti[r] * facti[n-r] % 998244353
query.sort(key=cmp_to_key(cmp))
answer = [0] * t
ans = 1
l = 1
r = 1
modlim = 10 ** 15
for qi in query:
    L, R, id = qi
    while l > L:
        l -= 1
        ans = c(2*r, l+1) - 2*ans
        # if ans > modlim:
        #     ans %= 998244353
    while l < L:
        ans = (c(2*r, l+1) - ans) * facti[2]
        l += 1
        # if ans > modlim:
        #     ans %= 998244353
    while r > R:
        ans = ans - c(2*r-2, l-1)
        r -= 1
        # if ans > modlim:
        #     ans %= 998244353
    while r < R:
        r += 1
        ans = ans + c(2*r-2, l-1)
        # if ans > modlim:
        #     ans %= 998244353
    ans %= 998244353
    answer[id] = str(ans)
print("\n".join(answer))