#include<iostream>
#include<vector>
#include<queue>
#include<stack>
#include<algorithm>
#include<limits.h>
#include<math.h>
#include<map>
#include<set>
#include<unordered_map>
#include<unordered_set>
#include<iomanip>
#include<cstring>
#include<random>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using namespace std;
int n,m,k;
ll buy[100][1000];
ll sell[100][1000];
ll profit[100][100];
ll dist[100][100];
ll cost[100][100];
void solve(){
cin>>n>>m>>k;
for(int i=0;i<n;i++)
for(int j=0;j<k;j++)
cin>>buy[i][j]>>sell[i][j];
for(int i1=0;i1<n;i1++)
for(int i2=0;i2<n;i2++)
for(int j=0;j<k;j++)
if(sell[i2][j]!=-1&&buy[i1][j]!=-1)
profit[i1][i2]=max(profit[i1][i2],sell[i2][j]-buy[i1][j]);
for(int i1=0;i1<n;i1++)
for(int i2=0;i2<n;i2++)
dist[i1][i2]=1e18;
for(int i=0;i<m;i++){
int a,b,w;
cin>>a>>b>>w;
dist[a-1][b-1]=w;
}
for(int j=0;j<n;j++)
for(int i1=0;i1<n;i1++)
for(int i2=0;i2<n;i2++)
dist[i1][i2]=min(dist[i1][i2],dist[i1][j]+dist[j][i2]);
ll l=0,r=2e9;
while(l<r-1){
ll curr=(l+r)/2;
// does there exist a cycle with efficiency at least curr?
for(int i1=0;i1<n;i1++)
for(int i2=0;i2<n;i2++)
cost[i1][i2]=curr*min(dist[i1][i2],ll(1e18)/curr)-profit[i1][i2];
for(int j=0;j<n;j++)
for(int i1=0;i1<n;i1++)
for(int i2=0;i2<n;i2++)
cost[i1][i2]=min(cost[i1][i2],cost[i1][j]+cost[j][i2]);
bool has=false;
for(int i=0;i<n;i++)
if(cost[i][i]<=0)
has=true;
if(has)
l=curr;
else
r=curr;
}
cout<<l<<"\n";
}
int main(){
ios::sync_with_stdio(false);cout.tie(NULL);cin.tie(NULL);
//freopen("/Users/jakob/cp_testing/test.txt","r",stdin);freopen("output.out","w",stdout);
int t=1;//cin>>t;
while(t--)solve();
return 0;
}
/*
4 5 2
10 9 5 2
6 4 20 15
9 7 10 9
-1 -1 16 11
1 2 3
2 3 3
1 4 1
4 3 1
3 1 1
*/
