#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <cmath>
#include <map>
#include <string>
#include <ios>
#include <iomanip>
#include <deque>
#include <queue>
#include <list>
#include <stack>
#define FASTIO ios_base::sync_with_stdio(0); cin.tie(NULL);
using ll = long long;
using namespace std;
ll gcd(ll n1, ll n2)
{
if (n2 != 0)
return gcd(n2, n1 % n2);
else
return n1;
}
ll lcm(ll a, ll b) {
return a * b / (gcd(a, b));
}
ll pv(ll a, ll b) {
if (b == 0)return 1;
ll res = pv(a, b / 2);
if (b % 2) {
return (res * res) * a;
}
else {
return (res * res);
}
}
vector<vector<pair<ll, ll>>>gp;
void solve() {
ll n, m, k; cin >> n >> m >> k;
gp = vector<vector<pair<ll, ll>>>(n);
vector<vector<ll>>apr(n, vector<ll>(2 * k));
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < 2 * k; j++) {
cin >> apr[i][j];
}
}
vector<vector<ll>>d(n, vector<ll>(n, 1e18)), max_delta(n, vector<ll>(n));
for (ll i = 0; i < m; i++) {
ll u, v, w; cin >> u >> v >> w;
u--;
v--;
gp[u].push_back({ v,w });
d[u][v] = w;
}
for (ll k = 0; k < n; k++) {
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < n; j++) {
d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
}
}
}
for (ll i = 0; i < n; i++) {
for (ll j = 0; j < n; j++) {
for (ll e = 0; e < 2 * k; e += 2) {
if (apr[i][e] != -1 && apr[j][e + 1] != -1&&i!=j) {
max_delta[i][j] = max(apr[j][e+1] - apr[i][e], max_delta[i][j]);
}
}
}
}
// for(int i=0;i<n;i++){
// for(int j=0;j<n;j++){
// cout<<d[i][j]<<" ";
// }
// cout<<endl;
// }
ll l=0,r=1e11;
while(l+1<r){
vector<vector<ll>> d1(n, vector<ll>(n, -1e18));
ll a=0;
ll mid=(l+r)/2;
for(ll i=0;i<n;i++){
for(ll j=0;j<n;j++){
ll a=1e18/mid;
d1[i][j]=max_delta[i][j]-mid*min(a, d[i][j]);
}
}
for (ll k = 0; k < n; ++k) {
for (ll i = 0; i < n; ++i) {
for (ll j = 0; j < n; ++j) {
d1[i][j] = max(d1[i][j], d1[i][k] + d1[k][j]);
}
}
}
for(ll i=0;i<n;i++)if(d1[i][i]>=0)a=1;
if(a==1) l=mid;
else r=mid;
}
cout<<l<<endl;
}
signed main() {
FASTIO
ll t=1;
//cin >> t;
while (t--) {
solve();
}
}
