import io,os,sys

#https://recruit.gmo.jp/engineer/jisedai/blog/python_standard_io_with_bytesio/
buf = io.BytesIO()
MOD = 998244353
max_K = 5*10**5

fact    =[-1] * (max_K+1) #MOD下での階乗
inv     =[-1] * (max_K+1) #MOD下での逆元
fact_inv=[-1] * (max_K+1) #MOD下での階乗の逆元
fact[0]=fact[1]=1
inv[1] = 1
fact_inv[0]=fact_inv[1] = 1
for i in range(2,max_K+1):
    fact[i] = (fact[i-1]*i)%MOD
    inv[i] = (-inv[MOD%i]*(MOD//i))%MOD
    fact_inv[i] = (fact_inv[i-1]*inv[i])%MOD

def c(n,r):
    if n < 0 or r < 0 or r > n:
        return 0
    return (fact[n]*fact_inv[r])%MOD*fact_inv[n-r]%MOD
input = sys.stdin.readline
T = int(input())
block = 972
Qli = [[] for i in range(200001//block+1)]
for i in range(T):
    l,r = map(int,input().split())
    Qli[l//block].append(r*(200001)*(200001)+l*(200001)+i)
l = 0
r = 0
ans = 0
answers = [0]*T
f = 0
f2 = fact_inv[2]
for li in Qli:
    if len(li)==0:
        continue
    for x in sorted(li,reverse = f):
        R = x//((200001)*(200001))
        L = x//(200001)-R*(200001)
        i = x%(200001)
        while l > L:
            l -= 1
            ans =(c(2*r, l+1) - 2*ans)%MOD
        while l < L:
            ans = ((c(2*r, l+1) - ans) * fact_inv[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
        answers[i] = ans
    f^=1
print(*answers,sep="\n")