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

mod = 998244353
fact = [1]
mx = 5 * 10 ** 5 + 1
for i in range(1, mx):
    fact.append(fact[-1] * i % mod)
facti = []
for f in fact:
    facti.append(pow(f, mod-2, mod))

block = 900
t = int(input())
query = [[] for _ in range(2 * 10 ** 5 // block + 1)]
for i in range(t):
    n,m = map(int,input().split())
    query[n // block].append([m,n,i])
def c(n, r):
    if n < 0 or r < 0 or r > n:
        return 0
    return (fact[n] * facti[r] % mod) * facti[n-r] % mod
# query.sort(key=cmp_to_key(cmp))
answer = [0] * t
ans = 1
l = 1
r = 1
for i in range(len(query)):
    if not query[i]:
        continue
    query[i].sort(reverse=(i%2 == 1))
    for qi in query[i]:
        R, L, id = qi
        while l > L:
            l -= 1
            ans = (c(2*r, l+1) - 2*ans) % mod
        while l < L:
            ans = ((c(2*r, l+1) - ans) * facti[2]) % mod
            l += 1
        while r > R:
            ans = (ans - c(2*r-2, l-1)) % mod
            r -= 1
        while r < R:
            r += 1
            ans = (ans + c(2*r-2, l-1)) % mod
        answer[id] = str(ans)
print("\n".join(answer))