#include <bits/stdc++.h>
    
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
    
mt19937 rng((int) chrono::steady_clock::now().time_since_epoch().count());
    
const int MOD = 1e9 + 7;
const int MAXN = 4e5 + 5;
const int INF = 2e9;
 
ll tempo[MAXN], f[MAXN], fan[MAXN], need[MAXN], id[MAXN], ant[MAXN], to[20][MAXN], bbto[20][MAXN];
ll esq[MAXN], dir[MAXN], cost[20][MAXN], bbcost[20][MAXN], ed[MAXN], costEd[MAXN];

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

    int n, m, k, p, a, b;
    cin >> n >> m >> k >> p;
    for (int i = 0; i < m; i++) {
        cin >> a >> b;
        tempo[a] = b;
    }
    for (int i = 0; i < k; i++) {
        cin >> a;
        f[a] = 1;
    }
    if (p >= k) {
        cout << "0\n";
        return 0;
    }
    int lst = 0;
    for (int i = 1; i <= n; i++) {
        if (!tempo[i]) {
            id[i] = ++lst;
        }
    }
    lst = 0;
    ll sum = 0;
    for (int i = 1; i <= 2 * n; i++) {
        if (i <= n && !tempo[i]) {
            dir[lst++] = sum + 1;
            esq[lst] = sum + 1;
            sum = 0;
        }
        else if (i > n && !tempo[i - n]) {
            dir[lst++] = sum + 1;
            esq[lst] = sum + 1;
            sum = 0;
            break;
        }
        else {
            if (i > n)
                sum += tempo[i - n] + 1;
            else 
                sum += tempo[i] + 1;
        }
    }
    ll at = 1, mx = 0;
    for (int i = 1; i <= n; i++) {
        if (!tempo[i]) {
            if (f[i]) {
                fan[at] = 1;
                mx = at;
            }
            at++;
        }
    }

    // 1 ate qtd
    int qtd = lst - 1;
    for (int i = 1; i <= qtd; i++) {
        ant[i] = mx;
        if (fan[i]) mx = i;
    }
    for (int i = 1; i <= qtd; i++) {
        if (ant[i] < i) {
            need[i] = qtd - i + ant[i] + 1;
        }
        else {
            need[i] = qtd - ant[i] + i + 1;
        }
    }
    for (int i = 1; i <= qtd; i++) {
        to[0][i] = i % qtd + 1;
        cost[0][i] = dir[i];
    }
    for (int i = 1; i < 20; i++) {
        for (int j = 1; j <= qtd; j++) {
            to[i][j] = to[i - 1][to[i - 1][j]];
            cost[i][j] = cost[i - 1][j] + cost[i - 1][to[i - 1][j]];
        }
    }

    ll l = 0, r = 1e15;
    while (r > l + 1) {
        ll m = (l + r) / 2;

        // calculate bbto e bbcost
        for (int i = 1; i <= qtd; i++) {
            ll anda = 0, custo = 0, at = i;
            for (int j = 19; j >= 0; j--) {
                if (custo + cost[j][at] <= m) {
                    custo += cost[j][at];
                    at = to[j][at];
                    anda += (1 << j);
                }
            }
            costEd[i] = anda;
            ed[i] = at;
        }
        for (int i = 1; i <= qtd; i++) {
            bbto[0][i] = ed[ed[i]] % qtd + 1;
            bbcost[0][i] = costEd[i] + costEd[ed[i]] + 1;
            if (bbcost[0][i] > qtd) {
                bbcost[0][i] = qtd;
                bbto[0][i] = i;
            }
        }
        for (int i = 1; i < 20; i++) {
            for (int j = 1; j <= qtd; j++) {
                bbto[i][j] = bbto[i - 1][bbto[i - 1][j]];
                bbcost[i][j] = bbcost[i - 1][j] + bbcost[i - 1][bbto[i - 1][j]];
            }
        }

        // menor numero de shows se comecarmos em i
        ll mn = p + 1;
        for (int i = 1; i <= qtd; i++) {
            ll at = i, shows = 0;
            for (int j = 19; j >= 0; j--) {
                if (shows + bbcost[j][at] < need[i]) {
                    shows += bbcost[j][at];
                    at = bbto[j][at];
                }
            }
            mn = min(mn, shows + 1);
        }
        
        if (mn <= p) r = m;
        else l = m;
    }
    cout << r << '\n';
    return 0;    
}