#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define ff first
#define ss second
ll ttt;
const ll INF=1e18;
const ll MOD=1e9+7;
const ll N=107;
const ll K=1007;
ll n,m,k;
vector<int>g[N],rg[N];
vector<int>w[N];
vector<int>order;
bool tsused[N];
bool sccused[N];
vector<int>comp[N];
int compind[N];
ll b[K][N],s[K][N];
ll maxval[N];
ll dist[N][N];
void tsdfs(int v){
tsused[v]=true;
for(int to:g[v]){
if(!tsused[to]){
tsdfs(to);
}
}
order.push_back(v);
}
void topsort(){
for(int v=1;v<=n;v++){
if(!tsused[v]){
tsdfs(v);
}
}
reverse(order.begin(),order.end());
}
void sccdfs(int c, int v){
comp[c].push_back(v);
compind[v]=c;
sccused[v]=true;
for(int to:g[v]){
if(!sccused[to]){
sccdfs(c,to);
}
}
}
void SCC(){
topsort();
for(int v=1;v<=n;v++){
for(int to:g[v]){
rg[to].push_back(v);
}
}
int cur=1;
for(int v=1;v<=n;v++){
if(!sccused[v]){
sccdfs(cur,v);
cur++;
}
}
}
void floyd_warshall(){
for(int p=1;p<=n;p++){
for(int v=1;v<=n;v++){
for(int u=1;u<=n;u++){
dist[v][u]=min(dist[v][u],dist[v][p]+dist[p][u]);
}
}
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
// freopen("output.txt","w",stdout);
cin>>n>>m>>k;
for(int i=1;i<=n;i++){
for(int j=1;j<=k;j++){
cin>>b[i][j]>>s[i][j];
}
}
for(int v=1;v<=n;v++){
for(int u=1;u<=n;u++){
dist[v][u]=MOD;
}
}
for(int i=0;i<m;i++){
int x,y,t;
cin>>x>>y>>t;
g[x].push_back(y);
dist[x][y]=t;
}
floyd_warshall();
SCC();
ll ans=0;
for(int i=1;i<=k;i++){
for(int v=1;v<=n;v++){
if(compind[v]==compind[1]){
maxval[i]=max(maxval[i],(s[v][i]-b[1][i])/(dist[1][v]+dist[v][1]));
}
}
ans=max(ans,maxval[i]);
}
cout<<ans<<endl;
}
