#include "bits/stdc++.h"
using namespace std;
const int N = 1e2 + 5;
vector <pair <int, int>> v[N];
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n, m, k;
cin >> n >> m >> k;
vector <vector <int>> b(n+1, vector <int> (k+1, 0)), s(n+1, vector <int> (k+1, 0));
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 u1, u2, w;
cin >> u1 >> u2 >> w;
v[u1].push_back({u2, w});
}
priority_queue <pair <int, int>> q;
vector <vector <int>> dis(n+1, vector <int> (n+1, 1e9 + 5));
for(int i = 1; i <= n; i++) {
q.push({0, i});
dis[i][i] = 0;
while(!q.empty()) {
auto [w, x] = q.top();
q.pop();
w *= (-1);
if(dis[i][x] != w) continue;
for(auto [j, w_] : v[x]) {
if(dis[i][j] > w + w_) {
dis[i][j] = w + w_;
q.push({-dis[i][j], j});
}
}
}
}
int ans = 0;
for(int i = 2; i <= n; i++) {
for(int j = 1; j <= k; j++) {
if(b[1][j] == -1 or s[i][j] == -1) continue;
ans = max(ans, (s[i][j] - b[1][j]) / (dis[1][i] + dis[i][1]));
}
}
cout << ans << '\n';
return 0;
}
