#include <cstdio>
#include <algorithm>

const int N = 200000;
int n, m, k, p, dur[N], fan[N], l_fan[N], r_fan[N], fan_id[N], back_ind[N], dp[N], next[N];
long long cost[N];

int z(int x) {
	if (x >= n) return x -= n;
	if (x < 0) return x += n;
	return x;
}

bool test(int l1, int r1, int l2, int r2) {
	return l1 <= r2 && l2 <= r1;
}

bool inter(int x, int y) {
	int lx = l_fan[x];
	int rx = r_fan[x];
	int ly = l_fan[y];
	int ry = r_fan[y];
	if (lx > rx) rx += n;
	if (ly > ry) ry += n;
	return test(lx, rx, ly, ry) || test(lx, rx, ly + n, ry + n) || test(lx + n, rx + n, ly, ry);
}

long long test(long long val) {
	int ll = 0, rr = 0;
	long long dist_l = 0, dist_r = 0;
	while (dist_l + cost[z(ll - 1)] <= val) {
		ll = z(ll - 1);
		dist_l += cost[ll];
		if (!ll) return true;
	}
	for (int i = 0; i < n; ++i) {
		while (dist_l > val) {
			dist_l -= cost[ll];
			ll = z(ll + 1);
		}
		while (dist_r + cost[rr] <= val) {
			dist_r += cost[rr];
			rr = z(rr + 1);
		}
		if (fan_id[i] != -1) {
			l_fan[fan_id[i]] = ll;
			r_fan[fan_id[i]] = rr;
		}
		dist_l += cost[i];
		dist_r -= cost[i];
	}
	int fi;
	for (fi = 0; fi < k && l_fan[fi] > r_fan[fi]; ++fi);
	if (fi == k) return true;
	std::rotate(l_fan, l_fan + fi, l_fan + k);
	std::rotate(r_fan, r_fan + fi, r_fan + k);
	int ans = ~(1 << 31);
	for (int i = k - 1, j = k - 1; i >= 0; --i) {
		while (!inter(i, j)) {
			if (i == j) exit(1);
			--j;
		}
		if (j + 1 < k) {
			dp[i] = dp[j + 1] + 1;
			next[i] = next[j + 1];
		} else {
			dp[i] = 1;
			next[i] = r_fan[i];
		}
		if (next[i] <= r_fan[k - 1] && l_fan[k - 1] > r_fan[k - 1] && next[i] >= l_fan[0] || l_fan[0] == l_fan[i]) {
			ans = std::min(ans, dp[i]);
		}
	}
	return ans <= p;
}

int main() {
	scanf("%d%d%d%d", &n, &m, &k, &p);
	for (int i = 0; i < m; ++i) {
		int c, t;
		scanf("%d%d", &c, &t);
		--c;
		dur[c] = t;
	}
	for (int i = 0; i < k; ++i) {
		scanf("%d", fan + i);
		--fan[i];
	}
	int fi = 0;
	while (dur[fi]) ++fi;
	int nn = 0;
	for (int i = fi;;) {
		back_ind[i] = nn;
		do {
			i = z(i + 1);
			cost[nn] += 1 + dur[i];
		} while (dur[i]);
		++nn;
		if (i == fi) break;
	}
	n = nn;
	for (int i = 0; i < n; ++i) fan_id[i] = -1;
	for (int i = 0; i < k; ++i) {
		fan[i] = back_ind[fan[i]];
		fan_id[fan[i]] = i;
	}
	std::sort(fan, fan + k);
	long long l = 0, r = 1000000000000000;
	while (l < r) {
		long long m = l + r >> 1;
		if (test(m)) r = m;
		else l = m + 1;
	}
	printf("%lld\n", r);
	return 0;
}