#include <bits/stdc++.h>
#define CHECK cout << "ok" << endl
#define finish(x) return cout << x << endl, 0
typedef long long ll;
typedef long double ldb;
const int md = 1e9 + 7;
const ll inf = 1e18;
const int OO = 1;
const int OOO = 1;
using namespace std;
int n, m, k;
ll B[101][1001], S[101][1001];
ll D[101][101] = {}, W[101][101];
ll d[101][101];
ll dist[101], cnt[101];
bool check(ll x) {
for (int i = 0; i < n; i++) for (int j = 0; j < n; j++)
d[i][j] = W[i][j] - x * D[i][j];
for (int i = 0; i < n; i++) dist[i] = cnt[i] = 0;
for (int iter = 0; iter <= n; iter++) {
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++) {
if (i != j) {
if (make_pair(dist[j], cnt[j]) < make_pair(dist[i] + d[i][j], cnt[i] + 1)) {
if (iter == n) return true;
dist[j] = dist[i] + d[i][j];
cnt[j] = cnt[i] + 1;
}
}
}
}
return false;
}
void preprocess() {
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
if (i != j) {
for (int x = 0; x < k; x++)
if (B[i][x] != -1 && S[j][x] != -1)
W[i][j] = max(W[i][j], S[j][x] - B[i][x]);
}
for (int u = 0; u < n; u++)
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
D[i][j] = min(D[i][j], D[i][u] + D[u][j]);
}
int main() {
ios::sync_with_stdio(0), cin.tie(0);
cin >> n >> m >> k;
for (int i = 0; i < n; i++) {
for (int j = 0; j < k; j++)
cin >> B[i][j] >> S[i][j];
}
for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) {
W[i][j] = 0;
if (i != j) D[i][j] = inf;
}
for (int i = 0, u, v, w; i < m; i++) {
cin >> u >> v >> w;
--u, --v;
D[u][v] = w;
}
preprocess();
ll lo = 0, hi = 1e9 + 3, mid;
while (lo < hi) {
mid = (lo + hi + 1) / 2;
if (check(mid)) lo = mid;
else hi = mid - 1;
}
finish(lo);
}
