/**
* In the name of Allah
* We are nothing and you're everything
* author: najmuddin
**/
#include <bits/stdc++.h>
using namespace std;
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
#define int ll
const char nl = '\n';
const int N = 10005;
const int inf = 1e9+1;
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, m, k;
cin >> n >> m >> k;
vector<vector<int>> b(n+1, vector<int> (k+1)), s(n+1, vector<int> (k+1));
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= k; ++j)
cin >> b[i][j] >> s[i][j];
}
vector<tuple<int, int>> g[n+1]; // to where, lenght
for (int i = 0; i < m; ++i) {
int u, v, w; cin >> u >> v >> w;
g[u].push_back({v, w});
}
int dis[n+1][n+1];
for (int i = 0; i <= n; ++i)
for (int j = 0; j <= n; ++j)dis[i][j] = inf;
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> q; // dist, where are we.
for (int i = 1; i <= n; ++i) {
q.push({0, i});
while (!q.empty()) {
int u = q.top().second, w = q.top().first;
q.pop();
for (auto [j, c]: g[u]) {
if (dis[i][j] > w+c) {
q.push({w+c, j});
dis[i][j] = w+c;
}
}
}
}
int ans = 0;
for (int i = 2; i <= n; ++i) {
for (int j = 1; j <= k; ++j) {
if (b[1][j] == -1 || s[i][j] == -1)continue;
ans = max(ans, (s[i][j]-b[1][j])/(dis[1][i]+dis[i][1]));
}
}
cout << ans;
return 0;
}
