#include <bits/stdc++.h>
using namespace std;
struct product {
int buy;
int sell;
};
struct road {
int destination;
int travel_time;
};
const int INF = 1e9;
int n, m, k;
vector< vector<int> > shortest_distance(100 + 1, vector<int>(100 + 1, INF));
void floyd_warshall(vector< vector<road> > &graph) {
for (int i = 1; i <= n; i++) {
shortest_distance[i][i] = 0;
}
for (int i = 1; i <= n; i++) {
for (auto &j: graph[i]) {
shortest_distance[i][j.destination] = j.travel_time;
}
}
// The node that goes in between.
for (int k = 1; k <= n; k++) {
// The source node.
for (int i = 1; i <= n; i++) {
// The destination node.
for (int j = 1; j <= n; j++) {
if ((shortest_distance[i][k] + shortest_distance[k][j]) < shortest_distance[i][j]) {
shortest_distance[i][j] = (shortest_distance[i][k] + shortest_distance[k][j]);
}
}
}
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m >> k;
// products[market][product number];
vector< vector<product> > products(n + 1, vector<product>(k + 1));
vector< vector<road> > graph(n + 1);
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= k; j++) {
int b, s;
cin >> b >> s;
products[i][j].buy = b;
products[i][j].sell = s;
}
}
for (int i = 1; i <= m; i++) {
int v, w, t;
cin >> v >> w >> t;
graph[v].push_back({w, t});
}
floyd_warshall(graph);
// Go throught every product and market.
// Iterate through every product.
int most_efficient = 0;
for (int i = 1; i <= k; i++) {
// Iterate through every market.
for (int j = 2; j <= n; j++) {
int profit = products[j][i].sell - products[1][i].buy;
if (profit < 0) {
continue;
}
int time = shortest_distance[1][j] + shortest_distance[j][1];
most_efficient = max(most_efficient, (profit / time));
}
}
cout << most_efficient << '\n';
return 0;
}
