#include <bits/stdc++.h>
using namespace std;
typedef long double ld;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pair<int,int>> vpi;
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)
#define pb push_back
#define rsz resize
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define fi first
#define se second
int n,m,k;
int const N=1e2+3;
int const K=1e3+3;
ll b[N][K], s[N][K];
ll p[N][N];
ll d[N][N];
vpi adj[N];
ll d2[N][N];
int const INF=1e9+4;
bool ok(int r)
{
//cout<<"try "<<r<<'\n';
F0R(i,n)fill(d2[i],d2[i]+n,4e18);
F0R(i,n)
{
F0R(j,n)
{
if(d[i][j]==INF)continue;
d2[i][j]=r*d[i][j]-p[i][j];
}
}
//F0R(i,n)
//{
//F0R(j,n)cout<<d2[i][j]<<' ';
//cout<<'\n';
//}
F0R(x,n)
{
F0R(i,n)
{
F0R(j,n)d2[i][j]=min(d2[i][j],d2[i][x]+d2[x][j]);
}
}
//F0R(i,n)
//{
//F0R(j,n)cout<<d2[i][j]<<' ';
//cout<<'\n';
//}
F0R(i,n)if(d2[i][i]<=0)return 1;
return 0;
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n>>m>>k;
F0R(i,n)
{
F0R(j,k)
{
cin>>b[i][j]>>s[i][j];
}
}
F0R(i,m)
{
int v,w,t;
cin>>v>>w>>t;
--v;--w;
adj[v].pb({w,t});
}
F0R(i,n)
{
fill(p[i],p[i]+n,0);
F0R(j,n)
{
F0R(u,k)
{
if(s[j][u]==-1||b[i][u]==-1)continue;
p[i][j]=max(p[i][j],s[j][u]-b[i][u]);
}
}
}
F0R(i,n)fill(d[i],d[i]+n,INF);
F0R(i,n)trav(e,adj[i])d[i][e.fi]=e.se;
F0R(x,n)
{
F0R(i,n)
{
F0R(j,n)
{
d[i][j]=min(d[i][j],d[i][x]+d[x][j]);
}
}
}
int R=0;
R0F(i,30)
{
if(ok(R+(1<<i)))R+=(1<<i);
}
cout<<R<<'\n';
return 0;
}
