// Source: https://usaco.guide/general/io
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define eb emplace_back
const ll cap = 101;
vector<pair<ll,ll>> adj[cap];
vector<pair<ll,ll>> radj[cap];
ll dist1[cap];
ll distto1[cap];
priority_queue<pair<ll,ll>> pq, revpq;
void normdijkstra(ll st){
pq.push({0,st});
dist1[st] = 0;
while (!pq.empty()){
auto [d, u] = pq.top(); pq.pop();
d *= -1;
for (auto [s, w]: adj[u]){
if (dist1[u] + w < dist1[s]){
dist1[s] = dist1[u]+w;
pq.push({-dist1[s], s});
}
}
}
}
void revdijkstra(ll st){
revpq.push({0,st});
distto1[st] = 0;
while (!revpq.empty()){
auto [d, u] = revpq.top(); revpq.pop();
d *= -1;
for (auto [s, w]: radj[u]){
if (distto1[u]+w < distto1[s]){
distto1[s] = distto1[u]+w;
revpq.push({-distto1[s], s});
}
}
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
ll n, m, k; cin >> n >> m >> k;
vector<vector<ll>> b(n+1, vector<ll>(k));
vector<vector<ll>> s(n+1, vector<ll>(k));
fill(dist1, dist1+cap, 1e18);
fill(distto1, distto1+cap, 1e18);
for (ll i{}; i < n; i++){
for (ll j{}; j < k; j++){
cin >> b[i+1][j+1] >> s[i+1][j+1];
}
}
for (ll i{}; i < m; i++){
ll x, y, w; cin >> x >> y >> w;
adj[x].eb(y, w);
radj[y].eb(x, w);
}
normdijkstra(1);
revdijkstra(1);
ll ans = -1e18;
for (ll i=2; i <= n; i++){
for (ll j=1; j <= k; j++){
if (s[i][j] == -1) continue;
ans = max(ans, (s[i][j]-b[1][j])/(dist1[i]+distto1[i]));
}
}
cout << ans;
}
