#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
const int ln = 18;
int dp[400005][ln];
signed main(){
	cin.tie(nullptr)->sync_with_stdio(false);
	int n,m,k,p;
	cin >> n >> m >> k >> p;
	vector<int>psa(2*n+2);
	vector<int>bad(2*n+2);
	for(int i = 0; i<m; i++){
		int c,t;
		cin >> c >> t;
		psa[c] = t;
		psa[n+c] = t;
		bad[c] = bad[n+c] = 1;
	}
	for(int i = 1; i<=2*n+1; i++){
		psa[i] += psa[i-1]+1;
	}
	vector<int>good(2*n+2);
	for(int i = 1; i<=k; i++){
		int x;
		cin >> x;
		good[x] = 1;
		good[x+n] = 1;
	}
	vector<pair<int,int>>vals;
	for(int i = 1; i<=2*n+1; i++){
		if(bad[i])continue;
		vals.push_back({psa[i],i});
	}
	int low = -1; int high = (int)1e12;
	while(low + 1 < high){
		int mid = (low+high)/2;
		memset(dp,0,sizeof(dp));
		dp[2*n+1][0] = 2*n+1;
		for(int i = 2*n; i>=1; i--){
			if(good[i]){
				auto [sum,idx] = *--lower_bound(vals.begin(),vals.end(),make_pair(psa[i]+mid+1,0LL));
				auto [sum2,idx2]= *--lower_bound(vals.begin(),vals.end(),make_pair(sum+mid+1,0LL));
				dp[i][0] = min(idx2+1,2*n+1);
			}
			else{
				dp[i][0] = dp[i+1][0];
			}
		}
		for(int j = 1; j<ln; j++){
			for(int i = 1; i<=2*n+1; i++){
				dp[i][j] = dp[dp[i][j-1]][j-1];
			}
		}
		bool f = false;
		for(int i = 1; i<=n; i++){
			int x = i;
			for(int j = 0; j<ln; j++){
				if(p&(1<<j)){
					x = dp[x][j];
				}
			}
			if(x>=i+n){
				f = true;
			}
		}
		if(f)high = mid;
		else low = mid;
	}
	cout << high << '\n';
	return 0;
}