#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);
#define CY cout<<"YES"<<endl
#define CN cout<<"NO"<<endl
#define ll long long
#define ciN cin
#define itn int
#define pshb push_back
#define sz size()
#define vec vector<int>
#define vecl vector<long long>
#define fro for
#define Int int
#define stirng string
#define nedl endl
#define pi 3.141592653589793238463
#define endl '\n'
#define ull unsigned long long
#define pii pair<int,int>
#define pll pair<ll,ll>
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);
}
}
void solve() {
int n, m, k;
cin >> n >> m >>k;
vector<vecl> arn(n, vecl(k));
vector<vecl> cax(n, vecl(k));
for (int i = 0; i < n; i++) {
for (int j = 0; j < k; j++) {
int a, c; cin >> a >> c;
arn[i][j] = a;
cax[i][j] = c;
}
}
vector<vector<pii>> gp(n);
vector<vecl> d(n, vecl(n,1e18));
for (int i = 0; i < m; i++) {
int u, v, w; cin >> u >> v >> w;
gp[--u].pshb({--v,w });
gp[v].pshb({ u,w });
d[u][v] = w;
}
vector<vecl> delta(n, vecl(n));
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
for (int k1 = 0; k1 < k; k1++) {
if(arn[i][k1]!=-1 && cax[i][k1]!=-1)delta[i][j] = max(delta[i][j], cax[j][k1]-arn[i][k1]);
}
}
}
for (int k = 0; k < n; k++) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
}
}
}
ll l = 0, r = 1e11;
while (l + 1 < r) {
ll m = (l + r) / 2;
vector<vecl> d1(n, vecl(n,-1e18));
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
d1[i][j] = delta[i][j] - m* d[i][j];
}
}
for (int k = 0; k < n; k++) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
d1[i][j] = max(d1[i][j], d1[i][k] + d1[k][j]);
}
}
}
bool f = false;
for (int i = 0; i < n; i++) {
if (d1[i][i] >= 0)f = true;
}
if (f)l = m;
else r = m;
}
if (l == 0) {
cout << r << endl;
}
else {
cout << l << endl;
}
}
int main() {
FASTIO
// int t; cin >> t;
//while (t--)
solve();
}
