/*input
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
*/
#include<bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<long long,null_type,less_equal<long long>,rb_tree_tag,tree_order_statistics_node_update> indexed_set;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("bmi,bmi2,lzcnt,popcnt")
//order_of_key #of elements less than x
// find_by_order kth element
using ll=long long;
using ld=long double;
using pii=pair<ll,ll>;
#define f first
#define s second
#define pb push_back
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define FILL(n,x) memset(n,x,sizeof(n))
#define ALL(_a) _a.begin(),_a.end()
#define sz(x) (int)x.size()
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()),c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
const ll maxn=2e3+5;
const ll maxlg=__lg(maxn)+2;
const ll INF64=4e18;
const int INF=0x3f3f3f3f;
const ll MOD=998244353;
const ld PI=acos(-1);
const ld eps=1e-6;
#define lowb(x) x&(-x)
#define MNTO(x,y) x=min(x,(__typeof__(x))y)
#define MXTO(x,y) x=max(x,(__typeof__(x))y)
template<typename T1,typename T2>
ostream& operator<<(ostream& out,pair<T1,T2> P){
out<<P.f<<' '<<P.s;
return out;
}
template<typename T>
ostream& operator<<(ostream& out,vector<T> V){
REP(i,sz(V)) out<<V[i]<<((i!=sz(V)-1)?" ":"");
return out;
}
ll mult(ll a,ll b){
return a*b%MOD;
}
ll mypow(ll a,ll b){
a%=MOD;
if(a==0) return 0;
if(b<=0) return 1;
ll res=1LL;
while(b){
if(b&1) res=(res*a)%MOD;
a=(a*a)%MOD;
b>>=1;
}
return res;
}
int arr[105][maxn];
int n,m,k;
vector<pair<int,pii>> ed;
ll dist[105][105];
ll d[105][105];
ll add[105][105];
bool wk(ll mid){
REP(i,n) REP(j,n){
if(d[i][j]==INF64) dist[i][j]=-INF64;
else dist[i][j]=add[i][j]-d[i][j]*mid;
}
REP(k,n) REP(i,n) REP(j,n) MXTO(dist[i][j],dist[i][k]+dist[k][j]);
//REP(i,n) REP(j,n) cout<<i<<' '<<j<<' '<<dist[i][j]<<'\n';
REP(i,n) if(dist[i][i]>=0){
return true;
}
return false;
}
int32_t main(){
ios::sync_with_stdio(false),cin.tie(0);
cin>>n>>m>>k;
REP(i,n) REP(j,2*k) cin>>arr[i][j];
REP(i,n) REP(j,n) d[i][j]=INF64;
REP(i,m){
int a,b,c;
cin>>a>>b>>c;
--a,--b;
ed.pb({c,{a,b}});
d[a][b]=c;
}
REP(k,n) REP(i,n) REP(j,n) MNTO(d[i][j],d[i][k]+d[k][j]);
//REP(i,n) REP(j,n) cout<<i<<' '<<j<<' '<<d[i][j]<<'\n';
REP(i,n){
REP(j,n){
add[i][j]=0;
REP(a,k){
if(arr[i][a*2]!=-1 and arr[j][a*2+1]!=-1) MXTO(add[i][j],arr[j][a*2+1]-arr[i][a*2]);
}
//cout<<i<<' '<<j<<' '<<add[i][j]<<'\n';
}
}
ll l=0,r=INF;
while(l<r){
ll mid=(l+r+1)/2;
if(wk(mid)) l=mid;
else r=mid-1;
}
cout<<l;
}
