#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 100 + 7;
const int K = 1000 + 7;
int n, m, k;
vector<pair<int, int>> g[N];
ll b[N][K], s[N][K];
vector<ll> get_dist(int u) {
vector<ll> dist(n + 1, 1e18);
vector<bool> vis(n + 1);
priority_queue<pair<ll, int>> pq;
pq.push({0, u});
dist[u] = 0;
while (!pq.empty()) {
int u = pq.top().second;
pq.pop();
if (vis[u]) continue;
vis[u] = 1;
for (auto [v, c] : g[u]) {
if (dist[u] + c < dist[v]) {
dist[v] = dist[u] + c;
pq.push({-dist[v], v});
}
}
}
return dist;
}
ll give(int x, int y) {
ll ans = 0;
for (int i = 1; i <= k; ++i) if (s[y][i] != -1 && b[x][i] != -1) ans = max(ans, s[y][i] - b[x][i]);
return ans;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> m >> k;
for (int i = 1; i <= n; ++i) for (int j = 1; j <= k; ++j) cin >> b[i][j] >> s[i][j];
for (int i = 1; i <= m; ++i) {
int a, b, c;
cin >> a >> b >> c;
g[a].push_back({b, c});
g[b].push_back({a, c});
}
vector<vector<ll>> dist(n + 1);
for (int i = 1; i <= n; ++i) dist[i] = get_dist(i);
vector<vector<ll>> g(n + 1, vector<ll>(n + 1));
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
g[i][j] = give(i, j);
}
}
ll ans = 0;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
for (int k = 1; k <= n; ++k) {
if (i != j && j != k && k != i) {
ans = max(ans, (g[i][j] + g[j][k]) / (dist[i][j] + dist[j][k] + dist[k][i]));
}
}
}
}
cout << ans << "\n";
return 0;
}
