from math import radians
import sys,random

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    return (g1[n] * g2[r] % mod) * g2[n-r] % mod

mod = 998244353
N = 2*10**5
g1 = [1]*(N+1)
g2 = [1]*(N+1)
inverse = [1]*(N+1)

for i in range( 2, N + 1 ):
    g1[i]=( ( g1[i-1] * i ) % mod )
    inverse[i]=( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2[i]=( (g2[i-1] * inverse[i]) % mod )
inverse[0]=0

N,K = mi()
M = int(input())
L = [-1 for r in range(K+1)]
for _ in range(M):
    l,r = mi()
    L[r] = max(L[r],l)

first = [0 for r in range(K+1)]
for r in range(1,K+1):
    tmp = -1
    for l in range(r,-1,-1):
        tmp = max(tmp,L[l])
        if tmp<=l:
            first[r] = l
        else:
            break
    else:
        first[r] = 0

dp = [[0 for i in range(K+1)] for r in range(K+1)]
cum = [[0 for i in range(K+1)] for r in range(K+1)]
dp[0][0] = 1
cum[0][0] = 1
#print(first)
for r in range(1,K+1):
    if first[r]==0:
        dp[r][0] = 1
        cum[r][0] = cum[r-1][0] + 1
    else:
        cum[r][0] = cum[r-1][0]

    for i in range(1,K+1):
        if first[r]<=1:
            dp[r][i] = cum[r-1][i-1]
        else:
            dp[r][i] = (cum[r-1][i-1] - cum[first[r]-2][i-1]) % mod
        cum[r][i] = (cum[r-1][i] + dp[r][i]) % mod
        #for l in range(first[r],r+1):
            #dp[r][i] += dp[l-1][i-1]
            #dp[r][i] %= mod

#print(dp[K])
exp_poly = [0 for i in range(K+1)]
for i in range(K+1):
    for j in range(i+1):
        if j&1:
            exp_poly[i-j] -= cmb(i,j,mod) * dp[K][i] % mod
        else:
            exp_poly[i-j] += cmb(i,j,mod) * dp[K][i] % mod
        exp_poly[i-j] %= mod

res = 0
for i in range(K+1):
    res += exp_poly[i] * pow(i,N,mod)
    res %= mod

print(res)