#include<bits/stdc++.h>
#define int long long
#define fast register int

using namespace std;

const int N=1e3+10,MOD=998244353;

int n,m,l[N],r[N],ans=0,s[N];

bool flag[N][N],f[N];

signed main(){
	std::ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	
	cin>>n>>m;
	
	s[1]=1;
	
	for (fast i=2;i<=n;i++){
		s[i]=2*s[i-1]%MOD+1;
		s[i]%=MOD;
	} 
	
	for (fast i=1;i<=n;i++){
		cin>>l[i]>>r[i];
		
		for (fast j=l[i];j<=r[i];j++){
			flag[j][i]=true;
		}
	}
	
	for (fast i=1;i<=m;i++){
		int x; cin>>x;
		int cnt=0,cnt1=0;
		
		for (fast j=1;j<=n;j++){
			if (flag[x][j]==true&&f[j]==false){
				f[j]=true;
				cnt++;
			}
			else if (flag[x][j]==true&&f[j]==true){
				cnt1++;
			}
		} 
		
		ans+=s[cnt+cnt1]%MOD-s[cnt1]%MOD;
	}
	
	cout<<ans;
	
	return 0;
}