#include <bits/stdc++.h>
using namespace std;
long long n,m,k;
long long buy[105][1005],sell[105][1005];
long long adj[105][105],efficent[105][105];
long long profit[105][105];
const long long inf=10e15;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m >> k;
for(int i = 1;i <= n;i++){
for(int j = 1;j <= k;j++) cin >> buy[i][j] >> sell[i][j];
}
for(int i = 1;i <= n;i++){
for(int j = 1;j <= n;j++) adj[i][j] = inf;
}
for(int i = 1;i <= m;i++){
long long u,v,w;
cin >> u >> v >> w;
adj[u][v] = w;
}
for(int l = 1;l <= n;l++){
for(int i = 1;i <= n;i++){
for(int j = 1;j <= n;j++){
adj[i][j] = min(adj[i][j] , adj[i][l] + adj[l][j]);
}
}
}
for(int i = 1;i <= n;i++){
for(int j = 1;j <= n;j++){
if(adj[i][j] >= inf){
profit[i][j] = -inf;
continue;
}
for(int cnt = 1;cnt <= k;cnt++){
if(sell[j][cnt] == -1 || buy[i][cnt] == -1) continue;
profit[i][j] = max(profit[i][j] , sell[j][cnt] - buy[i][cnt]);
}
}
}
long long lower = 0,higher = inf;
while(lower<higher){
long long mid = (lower + higher + 1) / 2;
for(int i = 1;i <= n;i++){
for(int j = 1;j <= n;j++){
if(adj[i][j] >= inf) efficent[i][j] = -inf;
else efficent[i][j] = profit[i][j] - mid * adj[i][j];
}
}
for(int l=1;l<=n;l++){
for(int i = 1;i <= n;i++){
for(int j = 1;j <= n;j++){
if(adj[i][l] >= inf || adj[j][l] >= inf) continue;
efficent[i][j] = max(efficent[i][j] , efficent[i][l] + efficent[l][j]);
}
}
}
bool check = false;
for(int i = 1;i <= n;i++){
if(efficent[i][i] >= 0){
check = true;
break;
}
}
if(check) lower=mid;
else higher=mid-1;
}
cout << lower << '\n';
return 0;
}
