#define ATCODER #define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; using ld = long double; using pll = pair; using pdd = pair; //template using pq = priority_queue, greater>; #define FOR(i, a, b) for(ll i=(a); i<(b);i++) #define REP(i, n) for(ll i=0; i<(n);i++) #define ROF(i, a, b) for(ll i=(b-1); i>=(a);i--) #define PER(i, n) for(ll i=n-1; i>=0;i--) #define REPREP(i,j,a,b) for(ll i=0;i > #define VV2(type,n,m,val) vector< vector > val;val.resize(n);for(ll i;i #define VEC(type,n,val) vector val;val.resize(n) #define VL vector #define VVL vector< vector > #define VP vector< pair > #define SZ size() #define all(i) begin(i),end(i) #define SORT(i) sort(all(i)) #define BITI(i) (1<>i) & 1) != 0) #define ALLBIT(n) (ll(1)<v?v:n #define MP(a,b) make_pair(a,b) #define DET2(x1,y1,x2,y2) (x1)*(y2)-(x2)*(y1) #define DET3(x1,y1,z1,x2,y2,z2,x3,y3,z3) (x1)*(y2)*(z3)+(x2)*(y3)*(z1)+(x3)*(y1)*(z2)-(z1)*(y2)*(x3)-(z2)*(y3)*(x1)-(z3)*(y1)*(x2) #define INC(a) for(auto& v:a)v++; #define DEC(a) for(auto& v:a)v--; #define SQU(x) (x)*(x) #define L0 ll(0) #ifdef ATCODER #include using namespace atcoder; using mint = modint1000000007; using mint2 = modint998244353; #endif template vector read(size_t n) { vector ts(n); for (size_t i = 0; i < n; i++) cin >> ts[i]; return ts; } template void read_tuple_impl(TV&) {} template void read_tuple_impl(TV& ts) { get(ts).emplace_back(*(istream_iterator(cin))); read_tuple_impl(ts); } template decltype(auto) read_tuple(size_t n) { tuple...> ts; for (size_t i = 0; i < n; i++) read_tuple_impl(ts); return ts; } using val = ll; using func = ll; val op(val a, val b) { return a + b; } val e() { return 0; } val mp(func f, val a) { return a + f; } func comp(func f, func g) { return f + g; } func id() { return 0; } ll g; bool f(val a) { return a < g; } ll di[4] = { 1,0,-1,0 }; ll dj[4] = { 0,1,0,-1 }; ll si[4] = { 0,3,3,0 }; ll sj[4] = { 0,0,3,3 }; //ll di[4] = { -1,-1,1,1 }; //ll dj[4] = { -1,1,-1,1 }; //ll di8[8] = { 0,-1,-1,-1,0,1,1,1 }; //ll dj8[8] = { -1,-1,0,1,1,1,0,-1 }; class Dijkstra { public: Dijkstra(ll n) { size = n; edges.resize(n); dist0.resize(n); rev.resize(n); } // ---注：有向--- void addEdge(ll from, ll to, ll cost = 0) { edges[from].push_back({ to,cost }); } void SetDefaultDist(ll s) { dist0.assign(size, LLONG_MAX); rev.assign(size, -1); dist0[s] = 0; que.push(P(0, s)); } void CalcDist() { while (!que.empty()) { P p = que.top(); que.pop(); ll v = p.second; if (dist0[v] < p.first) continue; for (ll i = 0; i < edges[v].size(); i++) { edge e = edges[v][i]; if (dist0[e.to] > dist0[v] + e.cost) { dist0[e.to] = dist0[v] + e.cost; rev[e.to] = v; que.push(P(dist0[e.to], e.to)); } } } } void GetDist(ll s) { SetDefaultDist(s); CalcDist(); } // 基本データ ll size; // 点数 struct edge { ll to, cost; }; typedef pair P; priority_queue, greater

> que; vector> edges; vector dist0; vector rev; }; void solve() { ll n, m, p, y; cin >> n >> m >> p >> y; Dijkstra dj(n); REP(i, m) { ll a, b, c; cin >> a >> b >> c; a--; b--; dj.addEdge(a, b, c); dj.addEdge(b, a, c); } dj.GetDist(0); ll ans = 0; VL v(n, 1e18); REP(i, p) { ll d, e; cin >> d >> e; d--; CHMIN(v[d], e); } REP(i, n) { ll tmp = (y - dj.dist0[i]) / v[i]; CHMAX(ans, tmp); } cout << ans; return; } int main() { ll t = 1; //cin >> t; while (t--) { solve(); } return 0; }