#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int LOG = 18;
const int N = 1 << 18;

int f[N];
int g[LOG][N];
LL cnt[LOG][N];

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n, m, k, p;
	cin >> n >> m >> k >> p;
	if (p >= k)
	{
		cout << "0\n";
		return 0;
	}
	VI t(n), fan(n);
	while (m--)
	{
		int c;
		cin >> c;
		c--;
		cin >> t[c];
	}
	FOR(i, 0, k)
	{
		int d;
		cin >> d;
		d--;
		fan[d] = 1;
	}
	vector<LL> dist;
	int firstCity = 0;
	while (t[firstCity] != 0)
		firstCity++;
	VI goodCities = {firstCity};
	LL sum = 0;
	FOR(i, firstCity + 1, n)
	{
		if (t[i] == 0)
		{
			dist.PB(i - goodCities.back() + sum);
			goodCities.PB(i);
			sum = 0;
		}
		else
			sum += t[i];
	}
	FOR(i, 0, firstCity)
		sum += t[i];
	dist.PB(sum + n - goodCities.back() + firstCity);
	VI nextFan(SZ(goodCities));
	int nxtFan = -1;
	RFOR(i, SZ(goodCities), 0)
	{
		int city = goodCities[i];
		nextFan[i] = nxtFan;
		if (fan[city])
			nxtFan = i;
	}
	FOR(i, 0, SZ(goodCities))
		if (nextFan[i] == -1)
			nextFan[i] = nxtFan;
	LL fullCircle = accumulate(ALL(dist), 0LL);
	LL l = 0, r = fullCircle;
	while (r - l > 1)
	{
		LL mid = (l + r) / 2;
		int ptr = 0;
		LL s = 0;
		FOR(i, 0, SZ(goodCities))
		{
			while (ptr < i || s + dist[ptr % SZ(dist)] <= mid)
			{
				s += dist[ptr % SZ(dist)];
				ptr++;
			}
			s -= dist[i];
			f[i] = ptr % SZ(dist);
		}
		FOR(i, 0, SZ(goodCities))
		{
			int concert = f[i];
			int distLeft = concert - i;
			if (distLeft < 0)
				distLeft += SZ(goodCities);
			g[0][i] = nextFan[f[concert]];
			int distRight = g[0][i] - concert;
			if (distRight < 0)
				distRight += SZ(goodCities);
			cnt[0][i] = distLeft + distRight;
		}
		FOR(j, 1, LOG)
		{
			FOR(i, 0, SZ(goodCities))
			{
				g[j][i] = g[j - 1][g[j - 1][i]];
				cnt[j][i] = cnt[j - 1][i] + cnt[j - 1][g[j - 1][i]];
			}
		}
		bool ok = false;
		FOR(i, 0, SZ(goodCities))
		{
			if (!fan[goodCities[i]])
				continue;
			int curIndex = i;
			LL curCnt = 0;
			RFOR(j, LOG, 0)
			{
				if ((p >> j) & 1)
				{
					curCnt += cnt[j][curIndex];
					curIndex = g[j][curIndex];
				}
			}
			if (curCnt >= SZ(goodCities))
			{
				ok = true;
			}
		}
		if (ok)
			r = mid;
		else
			l = mid;
	}
	cout << r << "\n";
	return 0;
}