#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long ll;
const ll INF = 1e16;
int n, m, k;
ll buy[105][1005], sell[105][1005];
ll dist[105][105], max_profit[105][105];
bool check(ll x) {
vector<vector<ll>> g(n + 1, vector<ll>(n + 1, -INF));
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
if (i != j && dist[i][j] != INF)
g[i][j] = max_profit[i][j] - x * dist[i][j];
// Floyd-Warshall musbat siklni tekshirish uchun
for (int p = 1; p <= n; p++)
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
g[i][j] = max(g[i][j], g[i][p] + g[p][j]);
for (int i = 1; i <= n; i++)
if (g[i][i] >= 0) return true;
return false;
}
int main() {
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];
}
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++) dist[i][j] = (i == j ? 0 : INF);
for (int i = 0; i < m; i++) {
int u, v; ll t; cin >> u >> v >> t;
dist[u][v] = min(dist[u][v], t);
}
// 1. Eng qisqa yo'llar
for (int p = 1; p <= n; p++)
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
dist[i][j] = min(dist[i][j], dist[i][p] + dist[p][j]);
// 2. Maksimal foyda matritsasi
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
max_profit[i][j] = 0;
if (i == j || dist[i][j] == INF) continue;
for (int p = 1; p <= k; p++) {
if (buy[i][p] != -1 && sell[j][p] != -1)
max_profit[i][j] = max(max_profit[i][j], sell[j][p] - buy[i][p]);
}
}
}
// 3. Binar qidiruv
ll low = 0, high = 1e9, ans = 0;
while (low <= high) {
ll mid = (low + high) / 2;
if (check(mid)) { ans = mid; low = mid + 1; }
else high = mid - 1;
}
cout << ans << endl;
return 0;
}
