#include <iostream>
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll maxn = 2*1e5+5, INF = 1e9+9;
void solve(){
int n, m, k;
cin >> n >> m >> k;
vector<vector<ll>> buy(n+1, vector<ll>(k+1)), sell(n+1, vector<ll>(k+1));
for(int i = 1; i <= n; i++){
for(int j = 1; j <= k; j++){
cin >> buy[i][j] >> sell[i][j];
}
}
vector<vector<ll>> adj(n+1, vector<ll>(n+1, INF));
for(int i = 1; i <= m; i++){
ll u, v, w;
cin >> u >> v >> w;
adj[u][v] = w;
}
vector<vector<ll>> just_profit(n+1, vector<ll>(n+1, 0));
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
for(int v = 1; v <= k; v++){
if(buy[i][v] != -1 && sell[j][v] != -1){
just_profit[i][j] = max(just_profit[i][j], sell[j][v]-buy[i][v]);
}
}
}
}
vector<vector<ll>> shortest_path(n+1, vector<ll>(n+1, INF));
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
shortest_path[i][j] = adj[i][j];
}
}
for(int k = 1; k <= n; k++){
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
shortest_path[i][j] = min(shortest_path[i][j], shortest_path[i][k]+shortest_path[k][j]);
}
}
}
auto check = [&](ll x) -> bool{
vector<vector<ll>> f(n+1, vector<ll>(n+1, -INF));
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
f[i][j] = just_profit[i][j] - shortest_path[i][j]*x;
}
}
for(int k = 1; k <= n; k++){
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
f[i][j] = max(f[i][j], f[i][k]+f[k][j]);
}
}
}
for(int i = 1; i <= n; i++){
if(f[i][i] >= 0) return true;
}
return false;
};
ll l = 0, r = 1e9;
while(l <= r){
ll mid = (l+r)/2;
if(check(mid)){
l = mid+1;
}else{
r = mid-1;
}
}
cout << l-1;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
solve();
}
