#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define int long long
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<bool> vb;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef vector<pll> vll;
typedef tree<pii,null_type,less<pii>,rb_tree_tag,
tree_order_statistics_node_update> oset;
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define mid (l+r)/2
#define all(x) x.begin(),x.end()
#define FOR(i,a) for(int i=0;i<(a);i++)
#define FORE(i,a,b) for(int i=(a);i<(b);i++)
#define cont(x) for(auto el:x) cout<<el<<' ';cout<<endl;
#define contp(x) for(auto el:x) cout<<el.fi<<'-'<<el.se<<' ';cout<<endl;
#define sp <<" "<<
#define DEBUG(x) cout<<(#x) sp x<<endl
#define carp(a,b) (((a%MOD)*(b%MOD))%MOD)
#define topla(a,b) (((a%MOD)+(b%MOD))%MOD)
const ll INF=1e18;
const int MAXN=105;
const int MAXK=1e3+3;;
const int MOD=1e9+7;
int n,m,k;
int tut[MAXN][2*MAXK][2];
vii adj[MAXN];
int dist[MAXN][MAXN];
void dij(int bas){
FORE(i,1,n+1){
dist[bas][i]=INF;
}
dist[bas][bas]=0;
set<pii> s;
s.insert({0,bas});
while(!s.empty()){
auto el=*s.begin();
s.erase(el);
int nd=el.se;
for(auto [kom,cost]:adj[nd]){
if(dist[bas][kom]>dist[bas][nd]+cost){
if(dist[bas][kom]!=INF) s.erase({dist[bas][kom],kom});
dist[bas][kom]=dist[bas][nd]+cost;
s.insert({dist[bas][kom],kom});
}
}
}
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n>>m>>k;
FORE(i,1,n+1){
FORE(j,1,k+1){
cin>>tut[i][j][0]>>tut[i][j][1];
}
}
FOR(i,m){
int a,b,c;
cin>>a>>b>>c;
adj[a].pb({b,c});
}
int ans=0;
FORE(i,1,n+1) dij(i);
FORE(i,2,n+1){
if(dist[1][i]==INF or dist[i][1]==INF) continue;
//1den aldım
//i'de sattım
int mx=0;
FORE(urun,1,k+1){
if(tut[i][urun][1]==-1 or tut[1][urun][0]==-1) continue;
//cout<<"here" sp urun sp tut[i][urun][1] sp tut[1][urun][0]<<endl;
mx=max(mx,tut[i][urun][1]-tut[1][urun][0]);
}
ans=max(ans,mx/(dist[1][i]+dist[i][1]));
}
cout<<ans<<endl;
}
