#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize ("Ofast")
#define all(x) x.begin() , x.end()
#define sze(x) (ll)(x.size())
#define mp(x , y) make_pair(x , y)
#define wall cerr<<"--------------------------------------"<<endl
typedef long long int ll;
typedef pair<ll , ll> pll;
typedef pair<int , int> pii;
typedef long double db;
typedef pair<pll , ll> plll;
typedef pair<int , pii> piii;
typedef pair<pll , pll> pllll;
const ll maxn = 1e2 + 16 , maxk = 1e3 + 16 , md = 1e9 + 7 , inf = 1e10;
ll gcd(ll a , ll b){
if(a < b) swap(a , b);
if(b == 0) return a;
return gcd(b , a % b);
}
ll tav(ll n , ll k){
ll res = 1;
while(k > 0){
if(k & 1){
res *= n; res %= md;
}
n *= n; n %= md;
k >>= 1;
}
return res;
}
ll n , m , k;
ll w[maxn][maxn] , dis[maxn][maxn] , a[maxn][maxk] , b[maxn][maxk] , f[maxn][maxn];
vector<pll> adj[maxn];
priority_queue<pll , vector<pll> , greater<pll>> pq;
void dij(ll r){
pq.push({dis[r][r] = 0 , r});
while(!pq.empty()){
pll q = pq.top(); pq.pop();
if(dis[r][q.second] != q.first) continue;
ll v = q.second;
for(auto p : adj[v]){
ll i = p.first , w = p.second;
if(dis[r][i] > dis[r][v] + w){
dis[r][i] = dis[r][v] + w;
pq.push({dis[r][i] , i});
}
}
}
return;
}
bool check(ll x){
for(ll i = 0 ; i < n ; i++){
for(ll j = 0 ; j < n ; j++){
f[i][j] = 1ll * x * dis[i][j] - w[i][j];
}
f[i][i] = inf;
}
for(ll k = 0 ; k < n ; k++){
for(ll i = 0 ; i < n ; i++){
for(ll j = 0 ; j < n ; j++){
f[i][j] = min(f[i][j] , f[i][k] + f[k][j]);
}
}
}
for(ll i = 0 ; i < n ; i++){
if(f[i][i] <= 0) return true;
}
return false;
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin>>n>>m>>k;
for(ll i = 0 ; i < n ; i++){
for(ll j = 0 ; j < k ; j++){
cin>>a[i][j]>>b[i][j];
}
}
for(ll i = 0 ; i < n ; i++){
for(ll j = 0 ; j < n ; j++){
ll h = 0;
for(ll q = 0 ; q < k ; q++){
if(b[j][q] != -1 && a[i][q] != -1) h = max(h , b[j][q] - a[i][q]);
}
w[i][j] = h;
dis[i][j] = inf;
}
}
for(ll i = 0 ; i < m ; i++){
ll v , u , w;
cin>>v>>u>>w; v--; u--;
adj[v].push_back({u , w});
}
for(ll i = 0 ; i < n ; i++){
dij(i);
}
ll l = 0 , r = 1e9 + 112;
while(l < r - 1){
ll m = (r + l) >> 1;
if(check(m)){
l = m;
} else {
r = m;
}
}
cout<<l<<'\n';
return 0;
}
