#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define MAXN (1000005)
ll N,M,K;
ll buy[105][1005], sell[105][1005];
ll profit[105][105], graph1[105][105], graph2[105][105];
int main() {
ios_base::sync_with_stdio(false);cin.tie(0);
cin>>N>>M>>K;
for(ll i = 0;i < N;i++){
for(ll j = 0;j < N;j++){
graph1[i][j] = 1e18;
}
}
for(ll i = 0;i < N;i++){
for(ll j = 0;j < K;j++){
cin>>buy[i][j]>>sell[i][j]; //if buy[i][j] or sell[i][j] = -1 that means type j item cannot be bought/sold respectively at node i
}
}
for(ll i = 0;i < M;i++){
ll a,b,c;
cin>>a>>b>>c;
a--, b--;
graph1[a][b] = c; //directed edge from a to b with weight c
}
for(ll k = 0;k < N;k++){
for(ll i = 0;i < N;i++){
for(ll j = 0;j < N;j++){
graph1[i][j] = min(graph1[i][j],graph1[i][k] + graph1[k][j]);
}
}
}
for(ll i = 0;i < N;i++){
for(ll j = 0;j < N;j++){
for(ll k = 0;k < K;k++){ //note that this is not floyd warshall, just normal nested for loops to loop though buy[node i][item type k] and sell[node j][item type k]
if(buy[i][k] != -1 && sell[j][k] != -1){
profit[i][j] = max(profit[i][j],sell[j][k] - buy[i][k]); //if we buy at node i and then sell at node j, we can keep on buying the same type of most optimal item since there is infinite stock of the same type
}
}
}
}
ll high = 1e9 + 5;
ll low = 0;
while(high - low > 1){
ll mid = (high + low) / 2;
for(ll i = 0;i < N;i++){
for(ll j = 0;j < N;j++){
if(graph1[i][j] >= 1e18) graph2[i][j] = 1e18 - profit[i][j];
else graph2[i][j] = (mid * graph1[i][j]) - profit[i][j];
}
}
for(ll k = 0;k < N;k++){
for(ll i = 0;i < N;i++){
for(ll j = 0;j < N;j++){
graph2[i][j] = min(graph2[i][j],graph2[i][k] + graph2[k][j]);
}
}
}
bool hasnegativecycle = false;
for(ll i = 0;i < N;i++){
if(graph2[i][i] <= 0){
hasnegativecycle = true;
}
}
if(hasnegativecycle){
low = mid;
}else{
high = mid;
}
}
cout<<low<<'\n';
}
