#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF (int)1e18
#define f first
#define s second
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
int n, m, k;
const int N = 101;
const int K = 1e3 + 1;
int buy[N][K];
int sell[N][K];
vector <pair<int, int>> adj[N];
int floyd[N][N];
int best[N][N];
bool check(int x){
vector<vector<int>> ok(n + 1, vector<int>(n + 1, -INF));
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++){
if (floyd[i][j] == INF) continue;
ok[i][j] = best[i][j] - x * floyd[i][j];
}
}
for (int k = 1; k <= n; k++){
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++){
ok[i][j] = max(ok[i][j], ok[i][k] + ok[k][j]);
}
}
}
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++){
if (i != j && ok[i][j] + ok[j][i] >= 0) return true;
}
}
return false;
}
void Solve()
{
cin >> n >> m >> k;
for (int i = 1; i <= n; i++){
for (int j = 1; j <= k; j++){
cin >> buy[i][j] >> sell[i][j];
if (buy[i][j] == -1) buy[i][j] = INF;
if (sell[i][j] == -1) sell[i][j] = 0;
}
}
for (int i = 0; i < N; i++){
for (int j = 0; j < N; j++){
floyd[i][j] = INF;
}
}
for (int i = 1; i <= m; i++) {
int u, v, w; cin >> u >> v >> w;
adj[u].push_back({v, w});
floyd[u][v] = w;
}
for (int k = 1; k <= n; k++){
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++){
floyd[i][j] = min(floyd[i][j], floyd[i][k] + floyd[k][j]);
}
}
}
for (int i = 1; i <= n; i++){
for (int j = 1; j <= n; j++){
for (int i1 = 1; i1 <= k; i1++){
best[i][j] = max(best[i][j], sell[j][i1] - buy[i][i1]);
}
}
}
int lo = 0, hi = 1e9;
while (lo != hi){
int mid = (lo + hi + 1) / 2;
if (check(mid)) lo = mid;
else hi = mid - 1;
}
cout << lo << "\n";
}
int32_t main()
{
auto begin = std::chrono::high_resolution_clock::now();
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
//cout << "Case #" << i << ": ";
Solve();
}
auto end = std::chrono::high_resolution_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
return 0;
}
