/*
Normie's Template v2.0
*/
// Standard library in one include.
#include <bits/stdc++.h>
using namespace std;
// ordered_set library.
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set(el) tree<el,null_type,less<el>,rb_tree_tag,tree_order_statistics_node_update>
// AtCoder library. (Comment out these two lines if you're not submitting in AtCoder.) (Or if you want to use it in other judges, run expander.py first.)
//#include <atcoder/all>
//using namespace atcoder;
//Pragmas (Comment out these three lines if you're submitting in szkopul.)
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//File I/O.
#define FILE_IN "cseq.inp"
#define FILE_OUT "cseq.out"
#define ofile freopen(FILE_IN,"r",stdin);freopen(FILE_OUT,"w",stdout)
//Fast I/O.
#define fio ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define nfio cin.tie(0);cout.tie(0)
#define endl "\n"
//Order checking.
#define ord(a,b,c) ((a>=b)and(b>=c))
//min/max redefines, so i dont have to resolve annoying compile errors.
#define min(a,b) (((a)<(b))?(a):(b))
#define max(a,b) (((a)>(b))?(a):(b))
//Constants.
#define MOD (ll(998244353))
#define MAX 300001
#define mag 320
//Pairs and 3-pairs.
#define p1 first
#define p2 second.first
#define p3 second.second
#define fi first
#define se second
#define pii(element_type) pair<element_type,element_type>
#define piii(element_type) pair<element_type,pii(element_type)>
//Quick power of 2.
#define pow2(x) (ll(1)<<x)
//Short for-loops.
#define ff(i,__,___) for(int i=__;i<=___;i++)
#define rr(i,__,___) for(int i=__;i>=___;i--)
//Typedefs.
#define bi BigInt
typedef long long ll;
typedef long double ld;
typedef short sh;
//---------END-------//
vector<piii(ll)> gt[101];
ll b[101][1001],s[101][1001];
ll dis[101][101];
ld cur[101];
ll eu[10001],ew[10001],ev[10001];
ll n,m,i,j,k,t,t1,u,v,a;
ll check(ll mul)
{
// cout<<"\ncheck "<<mul<<endl;
for (ll i=1;i<=n;i++) cur[i]=9e18;
cur[1]=0;
for (ll cnt=0;cnt<2*n;cnt++)
{
u=0;
for (ll i=1;i<=n;i++)
{
for (piii(ll) g : gt[i])
{
// cout<<"relax "<<i<<' '<<g.fi<<' '<<cur[i]<<' '<<cur[g.fi]<<' '<<(ld)cur[i]-g.se.fi-(1e-9)+g.se.se*mul<<endl;
if (cur[g.fi]>(ld)cur[i]-g.se.fi-(1e-9)+g.se.se*mul)
{
cur[g.fi]=(ld)cur[i]-g.se.fi-(1e-9)+g.se.se*mul;
u=1;
}
}
}
// cout<<cnt<<endl;
// for (ll i=0;i<n;i++) cout<<cur[i]<<' ';
if (!u) return 0;
}
return 1;
}
ll bs(ll l, ll r)
{
ll mid=(l+r)/2+1;
if (l==r) return l;
if (check(mid)) return bs(mid,r);
else return bs(l,mid-1);
}
int main()
{
fio;
cin>>n>>m>>t;
for (i=1;i<=n;i++)
{
for (j=1;j<=t;j++)
{
cin>>b[i][j]>>s[i][j];
}
for (j=1;j<=n;j++)
{
dis[i][j]=2e9;
}
dis[i][i]=0;
}
for (i=1;i<=m;i++)
{
cin>>eu[i]>>ev[i]>>ew[i];
dis[eu[i]][ev[i]]=min(dis[eu[i]][ev[i]],ew[i]);
gt[eu[i]].push_back({ev[i],{0,ew[i]}});
//cout<<eu[i]<<' '<<ev[i]<<' '<<0<<' '<<ew[i]<<endl;
}
for (k=1;k<=n;k++)
for (i=1;i<=n;i++)
for (j=1;j<=n;j++)
{
dis[i][j]=min(dis[i][j],dis[i][k]+dis[k][j]);
}
for (i=1;i<=n;i++) for (j=1;j<=n;j++) if (dis[i][j]!=2e9)
{
u=-2e9-7;
for (k=1;k<=t;k++) if ((b[i][k]!=-1)and(s[j][k]!=-1)) u=max(u,s[j][k]-b[i][k]);
if (u>0) gt[i].push_back({j,{u,dis[i][j]}});
//if (u>0) cout<<i<<' '<<j<<' '<<u<<' '<<dis[i][j]<<endl;
}
cout<<bs(0,1e9);
}
