#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define pb push_back
#define ss second
#define ff first
#define vt vector
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int inf = 2e9;
const int mod = 1e9+7;
const int maxn = 100 + 1;
int to[maxn][maxn];
void solve() {
int n, m, k;
cin >> n >> m >> k;
int b[n][k], s[n][k];
int p[n][n], dist[n][n];
vt<pii> g[n];
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++)p[i][j] = -1, dist[i][j] = inf;
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++){
for(int o = 0; o < k; o++){
if(b[i][o] != -1)to[i][j] = max(to[i][j], s[j][o] - b[i][o]);
}
}
}
for(int i = 0, u, v, d; i < m; i++){
cin >> u >> v >> d;
--u, --v;
g[u].pb({v, d});
}
for(int i = 0; i < n; i++){
priority_queue<pii, vt<pii>, greater<pii>> pq;
pq.push({0, i});
dist[i][i] = 0, p[i][i] = i;
while(!pq.empty()){
pii nw = pq.top();
pq.pop();
if(dist[i][nw.ss] != nw.ff)continue;
for(auto j : g[nw.ss]){
if(dist[i][j.ff] > nw.ff + j.ss){
dist[i][j.ff] = nw.ff + j.ss;
p[i][j.ff] = nw.ss;
pq.push({dist[i][j.ff], j.ff});
}
}
}
}
ll ans = 0;
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
if(i == j || dist[i][j] == inf || dist[j][i] == inf)continue;
int x = i;
ll dd = dist[i][j] + dist[j][i];
vt<int> path;
while(x != j){
path.pb(x);
x = p[j][x];
}
while(x != i){
path.pb(x);
x = p[i][x];
}
path.pb(i);
reverse(all(path));
int sz = path.size();
vt<ll> dp(sz, 0);
for(int o = 1; o < sz; o++){
for(int j = 0; j < o; j++){
dp[o] = max(dp[o], dp[j] + to[path[j]][path[o]]);
}
}
ans = max(ans, dp[sz - 1] / dd);
}
}
cout << ans;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int times = 1;
//cin >> times;
for(int i = 1; i <= times; i++) {
solve();
}
return 0;
}
