#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define sz(a) a.size()
#define all(a) a.begin(),a.end()
#define lb lower_bound
#define ub upper_bound
#define owo ios_base::sync_with_stdio(0);cin.tie(0);
#define MOD (ll)(1e9+7)
#define INF (ll)(1e18)
#define debug(...) fprintf(stderr, __VA_ARGS__),fflush(stderr)
#define time__(d) for(long blockTime = 0; (blockTime == 0 ? (blockTime=clock()) != 0 : false);\
debug("%s time : %.4fs\n", d, (double)(clock() - blockTime) / CLOCKS_PER_SEC))
typedef long long int ll;
typedef long double ld;
typedef pair<ll,ll> PII;
typedef pair<int,int> pii;
typedef vector<vector<int>> vii;
typedef vector<vector<ll>> VII;
ll gcd(ll a,ll b){if(!b)return a;else return gcd(b,a%b);}
VII dist(101,vector<ll>(101,INF));
VII profit(101,vector<ll>(101,0)),s(101,vector<ll>(1001,0)),b(101,vector<ll>(1001,0));
int main()
{
int n,m,x;
cin>>n>>m>>x;
for(int i=1;i<=n;i++){
for(int j=0;j<x;j++){
cin>>b[i][j]>>s[i][j];
}
}
for(int i=0;i<m;i++){
int v,u,t;
cin>>v>>u>>t;
dist[v][u] = t;
}
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
for(int k=1;k<=n;k++){
dist[j][k] = min(dist[j][k],dist[j][i]+dist[i][k]);
}
}
}
ll ans = 0;
for(int i=2;i<=n;i++){
ll mx = 0;
for(int k=0;k<x;k++){
mx = max(mx,s[i][k] - b[1][k]);
}
ans = max(ans,mx/(dist[1][i]+dist[i][1]));
}
cout<<ans;
}
