// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx")
// #pragma comment(linker, "/stack:200000000"]

#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <unordered_set>
#include <unordered_map>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <bitset>
#include <stack>
#include <random>
#include <fstream>
#include <sstream>
#include <chrono>

#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
#define hm unordered_map
#define pii pair<int, int>
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define cinv(v) for (auto& x: v) cin >> x
#define fr(i, n) for (int i = 0; i < n; ++i)
#define fl(i, l, n) for (int i = l; i < n; ++i)

// #define int ll

using namespace std;

#ifdef __LOCAL
	#define dbg(x) cerr << #x << " : " << x << '\n'
	const int maxn = 2e5 + 20;
#else
	#define dbg(x)
	const int maxn = 2e5 + 20;
#endif

//tg: @galebickosikasa

ostream& operator << (ostream& out, vector<int>& v) {
	for (auto& x: v) out << x << ' ';
	return out;
}

ostream& operator << (ostream& out, pii& v) {
	out << v.fi << ", " << v.se;
	return out;
}

ostream& operator << (ostream& out, vector<pii>& v) {
	for (auto& x: v) out << x << '\n';
	return out;
}

istream& operator >> (istream& in, pii& a) {
	in >> a.fi >> a.se;
	return in;
}

const ll inf = (ll) 2e9;
const ll kek = 2e18;
const ld pi = asin (1) * 2;
const ld eps = 1e-8;
const ll mod = (ll)1e9 + 7;
const ll ns = 97;
const int maxs = 1e6 + 20;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

multiset<int> answers;
int parent[maxn], sz[maxn], colors[maxn], pr[maxn], pos[maxn], order[maxn];
ll dist[maxn];
vector<pii> g[maxn];
int j = 0;

void dfs (int v, int p = -1) {
	parent[v] = p;
	order[j++] = v;
	// dbg (v);
	// dbg (dist[v]);
	sz[v] = 1;
	for (auto& u: g[v]) {
		int to = u.fi, c = u.se;
		if (to == p) continue;
		dist[to] = dist[v] + (ll)c;
		dfs (to, v);
		sz[v] += sz[to];
	}
}

struct DSU {
	vector<int> dsu;

	DSU (int s = maxn) {
		dsu = vector<int> (s);
		fr (i, s) dsu[i] = i;
	}

	int get (int x) {
		if (dsu[x] == x) return x;
		return dsu[x] = get (dsu[x]);
	}

	bool join (int a, int b) {
		int x = get (a), y = get (b);
		if (x != y) {
			dsu[x] = y;
			return 1;
		}
		return 0;
	}
};

struct edge {
	int a, b, c;

	bool operator < (const edge& other) const {
		return c < other.c;
	}
};

vector<edge> edges;

struct Tree {
	Tree* left;
	Tree* right;
	int priority, color, mx, mn;
	ll value;

	Tree (ll d, int x) {
		left = right = nullptr;
		priority = rnd ();
		value = d;
		color = mx = mn = x;
	}
};

int get_mn (Tree* t) {
	if (t == nullptr) return inf;
	return t->mn;
}

int get_mx (Tree* t) {
	if (t == nullptr) return -inf;
	return t->mx;
}

ll get_val (Tree* t) {
	if (t == nullptr) return -1;
	return t->value;
}

void render (Tree* t) {
	if (t == nullptr) return;
	t->mx = max (t->color, max (get_mx (t->left), get_mx (t->right)));
	t->mn = min (t->color, min (get_mn (t->left), get_mn (t->right)));
}

Tree* merge (Tree* l, Tree* r) {
	if (l == nullptr) return r;
	if (r == nullptr) return l;
	if (l->priority > r->priority) {
		l->right = merge (l->right, r);
		render (l);
		return l;
	} else {
		r->left = merge (l, r->left);
		render (r);
		return r;
	}
}

pair<Tree*, Tree*> split (Tree* t, ll x) {
	pair<Tree*, Tree*> ptt = {nullptr, nullptr};
	if (t == nullptr) return ptt;
	if (t->value > x) {
		ptt = split (t->left, x);
		t->left = ptt.se;
		ptt.se = t;
	} else {
		ptt = split (t->right, x);
		t->right = ptt.fi;
		ptt.fi = t;
	}
	render (t);
	return ptt;
}

Tree* erase (Tree* t, ll d, int x) {
	if (t == nullptr) return t;
	if (t->value == d && t->color == x) return merge (t->left, t->right);
	if (t->value > d) t->left = erase (t->left, d, x);
	else t->right = erase (t->right, d, x);
	render (t);
	return t;
}

Tree* add (Tree* t, Tree* a) {
	auto ptt = split (t, a->value);
	ptt.fi = merge (ptt.fi, a);
	return merge (ptt.fi, ptt.se);
}

Tree* add (Tree* t, ll d, int x) {
	Tree* a = new Tree (d, x);
	return add (t, a);
}

// void dfs (Tree* t) {
// 	if (t == nullptr) return;
// 	dfs (t->left);
// 	dbg (t->value);
// 	dbg (t->color);
// 	dfs (t->right);
// }

ll down (Tree* t, int new_color) {
	if (t == nullptr || (t->mn == new_color && t->mx == new_color)) return kek;
	ll ans = kek;
	// dbg (t->value);
	// dfs (t);
	// dbg ("exit");
	// dbg (get_val (t->left));
	// dbg (get_val (t->right));
	if (t->color != new_color) ans = t->value;
	if (get_mn (t->left) == inf || (get_mn (t->left) == new_color && get_mx (t->left) == new_color)) {
		ans = min (ans, down (t->right, new_color));
		// dbg ("right");
		// dbg (ans);
		return ans;
	}
	ans = min (ans, down (t->left, new_color));
	// dbg ("left");
	// dbg (ans);
	return ans;
}

struct ST {
	vector<Tree*> t;
	int size = 0, capacity;

	ST (int s = maxn) {
		while ((1<<size) < s) ++size;
		++size;
		size = (1<<size);
		capacity = (size>>1);
		t = vector<Tree*> (size, nullptr);
		vector<vector<pii>> tmp (size);
		fr (i, j) {
			tmp[i + capacity].pb ({dist[order[i]], colors[order[i]]});
			t[i + capacity] = add (t[i + capacity], dist[order[i]], colors[order[i]]);
		}
		for (int i = capacity - 1; i > 0; --i) {
			for (auto& x: tmp[i * 2]) tmp[i].pb (x);
			for (auto& x: tmp[i * 2 + 1]) tmp[i].pb (x);
			// dbg (i);
			// dbg (tmp[i]);
			for (auto& x: tmp[i]) t[i] = add (t[i], x.fi, x.se);
		}
	}

	ll upd (int cur, int left, int right, int l, int r, int new_color) {
		if (cur >= size) return kek;
		if (left > r || right < l) return kek;
		if (l <= left && r >= right) {
			// dbg ("open");
			// dbg (cur);
			return down (t[cur], new_color);
		}
		return min (upd (cur * 2, left, (left + right) / 2, l, r, new_color), upd (cur * 2 + 1, (left + right) / 2 + 1, right, l, r, new_color));
	}

	ll upd (int l, int r, int new_color) {
		return upd (1, 0, capacity - 1, l, r, new_color);
	}

	void upd (int v, int new_color) {
		if (v < 0) {
			v *= -1;
			ll x = upd (pos[v] + 1, pos[v] + sz[v] - 1, new_color) - dist[v];
			int p = pr[v];
			if (p < inf) {
				auto it = answers.find (p);
				if (it != answers.end ()) answers.erase (it);
			}
			if (x + dist[v] < inf) answers.insert (x), pr[v] = x;
			return;
		}

		if (sz[v] <= 1) {
			int u = pos[v] + capacity;
			// dbg (u);
			int p = colors[v];
			while (u) {
				// dbg ("here");
				// dfs (t[u]);
				t[u] = erase (t[u], dist[v], p);
				// dbg (dist[v]);
				// dbg (p);
				// dbg ("cont");
				// dfs (t[u]);
				t[u] = add (t[u], dist[v], new_color);
				// dbg ("end");
				// dfs (t[u]);
				u /= 2;
			}
			return;
		}
		int u = pos[v] + capacity;
		// dbg (u);
		int p = colors[v];
		while (u) {
			// dbg ("here");
			// dfs (t[u]);
			t[u] = erase (t[u], dist[v], p);
			// dbg (dist[v]);
			// dbg (p);
			// dbg ("cont");
			// dfs (t[u]);
			t[u] = add (t[u], dist[v], new_color);
			// dbg ("end");
			// dfs (t[u]);
			u /= 2;
		}
		ll x = upd (pos[v] + 1, pos[v] + sz[v] - 1, new_color) - dist[v];
		// dbg (v);
		// dbg (x);
		p = pr[v];
		// dbg (p);
		if (p < inf) {
			auto it = answers.find (p);
			if (it != answers.end ()) answers.erase (it);
		}
		if (x + dist[v] < inf) answers.insert (x), pr[v] = x;
	}
};



signed main () {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	int n, m, d, q;
	cin >> n >> m >> d >> q;
	fr (i, m) {
		int a, b, c;
		cin >> a >> b >> c;
		edges.pb ({a, b, c});
	}
	sort (all (edges));
	DSU dsu (n + 1);
	for (auto& e: edges) {
		if (dsu.join (e.a, e.b)) {
			g[e.a].pb ({e.b, e.c}), g[e.b].pb ({e.a, e.c});
		}
	}
	dfs (1);
	// fr (i, n) dbg (dist[i + 1]);
	// dbg (order);
	fr (i, j) {
		pos[order[i]] = i;
	}
	fr (i, n) {
		int x;
		cin >> x;
		colors[i + 1] = x;
	}
	for (auto& x: pr) x = inf;
	ST goo (n + 1);
	fr (i, n) goo.upd (i + 1, colors[i + 1]);
	// for (auto& x: answers) dbg (x);
	// dbg ("BEGIN");
	fr (i, q) {
		int v, x;
		cin >> v >> x;
		goo.upd (v, x);
		colors[v] = x;
		if (parent[v] != -1) goo.upd (-parent[v], colors[parent[v]]);
		cout << *answers.begin () << '\n';
		// dbg ("NEXT");
	}







}