#include<bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using mint=modint998244353; //1000000007;
using ll=long long;
using pp=pair<int,int>;
#define sr string 
#define vc vector
#define fi first
#define se second
#define rep(i,n) for(int i=0;i<(int)n;i++)
#define pb push_back
#define all(v) v.begin(),v.end()
#define pque priority_queue
#define bpc(a) __builtin_popcount(a)
int op(int a,int b){return max(a,b);}
int e(){return -1e8;}
int main(){
	int h,w,n,p;cin>>h>>w>>n>>p;
	map<int,vc<int>>m;
	rep(i,n){
		int a,b;
		cin>>a>>b; a--;b--;
		m[a].pb(b);
	}
	for(auto&[z,a]:m)sort(all(a));
	segtree<int,op,e>sg(w);
	sg.set(0,0);
	for(auto [z,v]:m){
		for(auto x:v){
			int a=sg.prod(0,x+1);
			sg.set(x,a+1);
		}
	}
	int ax=sg.prod(0,w+1);
	mint t=2; t/=p;
	mint ans=t.pow(ax);
	t/=2;
	ans*=t.pow(h+w-2-ax);
	cout<<ans.val();
}