#include <bits/stdc++.h>
// iostream is too mainstream
#include <cstdio>
// bitch please
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <cmath>
#include <iomanip>
#include <time.h>
#define dibs reserve
#define OVER9000 1234567890
#define ALL_THE(CAKE,LIE) for(auto LIE =CAKE.begin(); LIE != CAKE.end(); LIE++)
#define tisic 47
#define soclose 1e-8
#define chocolate win
// so much chocolate
#define patkan 9
#define ff first
#define ss second
#define abs(x) ((x < 0)?-(x):x)
#define uint unsigned int
#define dbl long double
#define pi 3.14159265358979323846
using namespace std;
// mylittledoge
typedef long long cat;
#ifdef DONLINE_JUDGE
// palindromic tree is better than splay tree!
#define lld I64d
#endif
int main() {
cin.sync_with_stdio(0);
cin.tie(0);
cout << fixed << setprecision(10);
int N,M,K;
cin >> N >> M >> K;
vector< vector<cat> > B(N,vector<cat>(K)), S(N,vector<cat>(K));
for(int i =0; i < N; i++) for(int j =0; j < K; j++) cin >> B[i][j] >> S[i][j];
vector< vector<cat> > D(N,vector<cat>(N,1e18));
for(int i =0; i < N; i++) D[i][i] =0;
for(int i =0; i < M; i++) {
int a,b,c;
cin >> a >> b >> c;
D[a-1][b-1] =min(D[a-1][b-1],1LL*c);}
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]);
vector< vector<cat> > gain(N,vector<cat>(N,0));
for(int i =0; i < N; i++) for(int k =0; k < K; k++) if(B[i][k] != -1)
for(int j =0; j < N; j++) if(S[j][k] > B[i][k]) gain[i][j] =max(gain[i][j],S[j][k]-B[i][k]);
cat ansA =0, ansB =OVER9000;
while(ansB-ansA > 1) {
int r =(ansA+ansB)/2;
vector< vector<cat> > cost(N,vector<cat>(N,-1e18));
for(int i =0; i < N; i++) for(int j =0; j < N; j++)
if(D[i][j] < 1e10) cost[i][j] =gain[i][j]-r*D[i][j];
for(int a =0; a < 10; a++) {
bool br =false;
for(int i =0; i < N; i++) for(int j =0; j < N; j++) if(i != j)
if(cost[i][j]+cost[j][i] >= 0) br =true;
if(br) break;
vector< vector<cat> > cost_nw =cost;
for(int i =0; i < N; i++) for(int j =0; j < N; j++) if(D[i][j] < 1e10)
for(int k =0; k < N; k++) if(D[j][k] < 1e10)
cost_nw[i][k] =max(cost_nw[i][k],cost[i][j]+cost[j][k]);
cost =cost_nw;}
bool ok =false;
for(int i =0; i < N; i++) for(int j =0; j < N; j++) if(i != j)
if(cost[i][j]+cost[j][i] >= 0) ok =true;
if(ok) ansA =r;
else ansB =r;}
cout << ansA << "\n";
return 0;}
// look at my code
// my code is amazing
