#include<bits/stdc++.h>
using namespace std;
#define int long long
const int MAXN = 101;
const int MAXK = 1001;
int sell[MAXN][MAXK];
int buy[MAXN][MAXK];
int p1[MAXN][MAXN];
int best[MAXN][MAXN];
int p2[MAXN][MAXN];
bool test(int r, int n){
for(int i = 0; i < n; ++i){
for(int j = 0; j < n; ++j){
if(p1[i][j] == INT_MAX){
p2[i][j] = 0;
}else{
p2[i][j] = best[i][j] - r * p1[i][j];
// cout << i << " " << j << " : ";
// cout << best[i][j] << " " << p1[i][j] << " : ";
// cout << p2[i][j] << "\n";
}
}
}
for(int k = 0; k < n; k++){
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
p2[i][j] = max(p2[i][j], p2[i][k] + p2[k][j]);
}
}
}
for(int i = 0; i < n; ++i){
// cout << r << " : " << i << " : " << p2[i][i] << endl;
if(p2[i][i] >= 0) return true;
}
return false;
}
int32_t main(){
cin.tie(NULL)->sync_with_stdio(false);
int n, m, k; cin >> n >> m >> k;
for(int i = 0; i < n; ++i){
for(int j = 0; j < k; ++j){
int ki = j / 2;
cin >> buy[i][ki];
cin >> sell[i][ki];
}
}
for(int i = 0; i < n; ++i){
for(int j = 0; j < n; ++j){
p1[i][j] = INT_MAX;
}
}
for(int i = 0; i < m; ++i){
int a, b, c; cin >> a >> b >> c;
a--; b--;
p1[a][b] = c;
}
for(int i = 0; i < n; ++i){
for(int j = 0; j < n; ++j){
for(int l = 0; l < k; ++l){
if(buy[i][l] > -1 && sell[j][l] > -1){
int prof = sell[j][l] - buy[i][l];
best[i][j] = max(prof, best[i][j]);
}
}
}
}
{
for(int l = 0; l < n; l++){
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
p1[i][j] = min(p1[i][j], p1[i][l] + p1[l][j]);
}
}
}
}
int ans = 0;
int pot = (1LL << 30);
while(pot){
int mans = ans + pot;
if(test(mans, n)) ans = mans;
pot /= 2;
}
cout << ans << "\n";
}
