#include <bits/stdc++.h>

using namespace std;

#define iter(v) v.begin(), v.end()
#define SZ(v) (int) v.size()
#define pb emplace_back
#define ff first
#define ss second

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

#ifdef zisk
void debug(){cout << endl;}
template<class T, class ... U>
void debug(T a, U ... b){
	cout << a << " ", debug(b...);
}
template<class T> void pary(T l, T r){
	while(l != r) cout << *l << " ", l++;
	cout << endl;
}
#else
#define debug(...) void()
#define pary(...) void()
#endif

template<class A, class B>
ostream& operator<<(ostream& o, pair<A, B> p){
	return o << '(' << p.ff << ',' << p.ss << ')';
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);

	int n, m, K, P;
	cin >> n >> m >> K >> P;
	vector<bool> qua(n);
	vector<ll> tpos(n);
	vector<bool> tfan(n);
	ll total = n;
	for(int i = 0; i < m; i++){
		int c, t;
		cin >> c >> t;
		qua[c - 1] = true;
		tpos[c - 1] = t;
		total += t;
	}
	for(int i = 0; i < K; i++){
		int p;
		cin >> p;
		tfan[p - 1] = true;
		//debug("tfan", p - 1, tfan[p - 1]);
	}
	tpos[0] = 1 + tpos[0];
	for(int i = 1; i < n; i++){
		tpos[i] = tpos[i - 1] + 1 + tpos[i];
	}
	//pary(iter(tpos));

	vector<ll> pos;
	vector<bool> fan;
	for(int i = 0; i < n; i++){
		if(qua[i]) continue;
		pos.pb(tpos[i]);
		fan.pb(tfan[i]);
		//debug("good", i, tpos[i], tfan[i]);
	}
	n = SZ(pos);
	ll off = total - pos.back();
	for(int i = 0; i < n; i++) pos[i] += off;
	//assert(pos.back() == total);
	vector<ll> fanpos;
	for(int i = 0; i < n; i++){
		if(fan[i]){
			fanpos.pb(pos[i]);
		}
	}
	/*pary(iter(pos));
	pary(iter(fan));
	pary(iter(fanpos));*/

	auto solve = [&](const ll p){
		//debug("solve", p);
		vector<vector<int>> f(20, vector<int>(n));
		for(int i = 0; i < n; i++){
			ll nxt;
			if(pos[i] + p < total)
				nxt = *upper_bound(iter(pos), pos[i] + p);
			else
				nxt = *upper_bound(iter(pos), pos[i] + p - total);
			ll fp;
			if(nxt <= fanpos.back()){
				fp = *lower_bound(iter(fanpos), nxt);
			}
			else{
				fp = fanpos[0];
			}

			if(fp + p < total + pos.front())
				f[0][i] = upper_bound(iter(pos), fp + p) - pos.begin() - 1;
			else
				f[0][i] = upper_bound(iter(pos), fp + p - total) - pos.begin() - 1;
		}
		//pary(iter(f[0]));
		vector<vector<ll>> flen(20, vector<ll>(n));
		for(int i = 0; i < n; i++){
			flen[0][i] = i < f[0][i] ? pos[f[0][i]] - pos[i] : pos[f[0][i]] + total - pos[i];
		}
		for(int i = 1; i < 20; i++){
			for(int j = 0; j < n; j++){
				f[i][j] = f[i - 1][f[i - 1][j]];
				flen[i][j] = flen[i - 1][j] + flen[i - 1][f[i - 1][j]];
			}
		}

		for(int i = 0; i < n; i++){
			ll cur = 0;
			int ans = 0;
			int now = i;
			for(int j = 19; j >= 0; j--){
				if(cur + flen[j][now] < total){
					cur += flen[j][now];
					now = f[j][now];
					ans += 1 << j;
				}
			}
			//debug("ok", i, ans);
			ans++;
			if(ans <= P) return true;
		}
		return false;

	};

	ll l = 0, r = total;
	while(l < r){
		ll mid = (l + r) / 2;
		if(solve(mid)) r = mid;
		else l = mid + 1;
	}
	cout << l << "\n";


}