#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define jizz ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define pb push_back
#define ET cout << "\n"
#define ALL(v) v.begin(),v.end()
#define MP make_pair
#define F first
#define S second
#define MEM(i,j) memset(i,j,sizeof i)
#define DB(a,s,e) {for(int i=s;i<e;++i) cout << a[i] << " ";ET;}
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const ll INF=1e18;
pll buy[105][1005];
ll dis[105][105],earn[105][105],dp[105][105];
int main()
{jizz
ll n,m,k,a,b,w,l=0,r=1e9;
cin >> n >> m >> k;
for(int i=1;i<=n;++i)
for(int j=0;j<k;++j)
cin >> buy[i][j].F >> buy[i][j].S;
for(int i=1;i<=n;++i)
for(int j=1;j<=n;++j)
dis[i][j]=INF;
while(m--)
cin >> a >> b >> w,dis[a][b]=min(w,dis[a][b]);
for(int k=1;k<=n;++k)
for(int i=1;i<=n;++i)
for(int j=1;j<=n;++j)
dis[i][j]=min(dis[i][j],dis[i][k]+dis[k][j]);
for(int i=1;i<=n;++i)
for(int j=1;j<=n;++j)
if(i!=j)
for(int t=0;t<k;++t)
if(~buy[i][t].F&&~buy[j][t].S)
earn[i][j]=max(earn[i][j],buy[j][t].S-buy[i][t].F);
while(l<r)
{
ll mid=(l+r)/2+1,tmp=-INF;
for(int i=1;i<=n;++i)
for(int j=1;j<=n;++j)
dp[i][j]=earn[i][j]-dis[i][j]*mid;
for(int k=1;k<=n;++k)
for(int i=1;i<=n;++i)
for(int j=1;j<=n;++j)
dp[i][j]=max(dp[i][j],dp[i][k]+dp[k][j]);
for(int i=1;i<=n;++i)
tmp=max(tmp,dp[i][i]);
if(tmp>=0) l=mid;
else r=mid-1;
}
cout << l << "\n";
}
