#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
const double PI = 4 * atan(1);
#define sz(x) (int)(x).size()
#define ll long long
#define ld long double
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define pii pair <int, int>
#define vi vector<int>
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
#define vpi vector<pair<int, int>>
#define vpd vector<pair<double, double>>
#define pd pair<double, double>
#define f0r(i,a) for(int i=0;i<a;i++)
#define f1r(i,a,b) for(int i=a;i<b;i++)
#define trav(a, x) for (auto& a : x)
void fast_io(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
}
void io(string taskname){
string fin = taskname + ".in";
string fout = taskname + ".out";
const char* FIN = fin.c_str();
const char* FOUT = fout.c_str();
freopen(FIN, "r", stdin);
freopen(FOUT, "w", stdout);
fast_io();
}
const int MAXN = 1e2 + 5;
const int MAXK = 1e3 + 5;
const ll INF = 1e18;
ll buy[MAXN][MAXK];
ll sell[MAXN][MAXK];
ll dist[MAXN][MAXN];
ll weight[MAXN][MAXN];
ll floyd[MAXN][MAXN];
ll floyd2[MAXN][MAXN];
//ll graph[MAXN][MAXN];
int n, m, k;
int check(ll r){
f0r(i, n){
f0r(j, n){
if(dist[i][j] == INF){
floyd[i][j] = -INF;
continue;
}
floyd[i][j] = (weight[i][j] - r*dist[i][j]);
// if(r == 3)cout << i + 1 << " " << j + 1 << " " << floyd[i][j] << endl;
// cout << graph[i][j] << endl;
floyd[i][j] = max(-INF, floyd[i][j]);
}
floyd[i][i] = -INF;
}
f0r(mid, n){
f0r(i, n){
f0r(j, n){
floyd[i][j] = max(floyd[i][j], floyd[i][mid] + floyd[mid][j]);
if(floyd[i][i]>= 0) return 1;
floyd[i][j] = min(floyd[i][j], INF);
floyd2[i][j] = floyd[i][j];
}
}
}
f0r(mid, n){
f0r(i, n){
f0r(j, n){
floyd2[i][j] = max(floyd2[i][j], floyd2[i][mid] + floyd2[mid][j]);
if(floyd2[i][j]>floyd[i][j]) return 1;
}
}
}
return 0;
}
int main(){
fast_io();
cin >> n >> m >> k;
f0r(i, n){
f0r(j, k){
int b, s;
cin >> b >> s;
buy[i][j] = b;
sell[i][j] = s;
}
}
f0r(i, MAXN){
f0r(j, MAXN){
dist[i][j] = INF;
}
}
f0r(i, m){
int u, v;
ll w;
cin >> u >> v >> w;
u--; v--;
dist[u][v] = min(dist[u][v], w);
}
f0r(i, n) dist[i][i] = 0;
f0r(mid, n){
f0r(i, n){
f0r(j, n){
dist[i][j] = min(dist[i][j], dist[i][mid] + dist[mid][j]);
}
}
}
f0r(i, n){
f0r(j, n){
if(i == j) continue;
f0r(it, k){
if(sell[j][it] == -1 || buy[i][it] == -1) continue;
weight[i][j] = max(weight[i][j], sell[j][it] - buy[i][it]);
}
}
}
ll lo = 0;
ll hi = 1e18;
while(abs(lo - hi)>1){
ll mid = (lo + hi)/2;
if(check(mid)){
lo = mid;
}
else{
hi = mid-1;
}
}
if(lo>hi) swap(lo, hi);
if(check(hi)) cout << hi << endl;
else cout << lo << endl;
// cout << check(3) << endl;
return 0;
}
