n,k = map(int,input().split())
mod = 998244353

LR = [list(map(int,input().split())) for i in range(n)]
M = 2*10**5+1
eL = [0]*M
eR = [0]*M
for l,r in LR:
    eL[l] += 1
    eR[r-1] += 1


now = 0
dp = 1
for l,r in zip(eL,eR):
    if l:
        for i in range(l):
            dp *= k-now
            dp %= mod
            now += 1
    
    now -= r

ans = pow(k,n,mod)-dp
print(ans%mod)