#include<bits/stdc++.h>
using namespace std;
int n , m , k;
const int N = 107;
const int K = 1003;
typedef long long ll;
ll buyData[N][K];
ll sellData[N][K];
ll cost[N][N];
bool reach[N][N];
bool mark[N];
pair<ll , ll> ans[N][N];
ll d[N][N];
vector<pair<int ,ll>> adj[N];
void getInput(){
memset(buyData , -1 , sizeof buyData);
memset(sellData , -1 , sizeof sellData);
cin >> n >> m >> k;
for(int i = 0; i < n; i++){
for(int j = 0; j < 2 * k; j++){
int co;
cin >> co;
if(j % 2 == 0) buyData[i][j / 2] = co;
else sellData[i][j / 2] = co;
}
}
for(int i = 0; i < m; i++){
int u , v;
ll w;
cin >> u >> v >> w;
u-- , v--;
adj[u].push_back({v , w});
adj[v].push_back({u , w});
}
}
void dfs(int u , int src){
mark[u] = true;
reach[src][u] = true;
for(auto v: adj[u]){
if(mark[v.first]) continue;
dfs(v.first , src);
}
}
void calcRech(){
for(int i = 0; i < n; i++){
memset(mark , 0 , sizeof mark);
dfs(i , i);
}
}
void calcCost(){
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
if(!reach[i][j]){
cost[i][j] = 1e18;
cost[j][i] = 1e18;
continue;
}
for(int f = 0; f < k; f++){
cost[i][j] = max(cost[i][j] , sellData[j][f] - buyData[i][f]);
}
}
}
}
void floydDis(){
for(int i = 0; i < n; i++) {
for(int j = 0; j < n; j++) d[i][j] = 1e17;
for(auto v: adj[i]){
d[i][v.first] = min(d[i][v.first] , v.second);
}
}
for(int i = 0; i < n; i++){
for(int u = 0; u < n; u++){
for(int v = 0; v < n; v++){
if(!reach[u][v]) continue;
d[u][v] = min(d[u][v] , d[u][i] + d[i][v]);
}
}
}
}
pair<ll ,ll> maxPair(pair<ll , ll> x , pair<ll ,ll> y){
if(x.first * y.second < x.second * y.first) return y;
return x;
}
void floydAns(){
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++) {
ans[i][j] = {1e18 , 1};
if(reach[i][j]) ans[i][j] = {cost[i][j] , d[i][j]};
}
}
for(int i = 0; i < n; i++){
for(int u = 0; u < n; u++){
for(int v = 0; v < n; v++){
if(u == v) continue;
if(!reach[u][v]) continue;
if(!reach[u][i] || !reach[i][v]) continue;
ans[u][v] = maxPair({ans[u][i].first + ans[i][v].first , ans[u][i].second + ans[i][v].second} , ans[u][v]);
}
}
}
}
ll getAns(){
pair<ll , ll> ansPair = {0 , 1};
for(int u = 0; u < n; u++){
for(int v = 0; v < n; v++){
if(u == v) continue;
if(!reach[u][v] || !reach[v][u]) continue;
ansPair = max(ansPair , {ans[u][v].first + ans[v][u].first , ans[u][v].second + ans[v][u].second});
}
}
return ansPair.first / ansPair.second;
}
int main(){
getInput();
calcRech();
calcCost();
floydDis();
floydAns();
cout << getAns() << endl;
return 0;
}
