#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long ll;
typedef double db;
typedef vector<long long> vl;
typedef pair<long long , long long > pl;
const int N=1e6+1;
#define po pop_back
#define pb push_back
#define mk make_pair
#define lw lower_bound
#define up upper_bound
#define ff first
#define ss second
#define boost ios_base::sync_with_stdio(); cin.tie(0); cout.tie(0);
#define MOD 1000000007
#define MAX 1e18
#define MIN -1e18
#define rep(i,a,b) for(ll i=a;i<=b;i++)
#define per(i,a,b) for(ll i=b;i>=a;i--)
#define con continue
#define freopen freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
#define PI 3.14159265358979323846264338327950288419716939937510582097494459230781640628
// typedef tree<ll , null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> indexed_set;
// template< typename T>
// using indexed_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
ll sz,n,m,ans,mid,mn,mx,cnt,T,sum,h1,h2,e[1234567],b[1234567],c[1234567],d[1<<20],k,i,j,l,r,h,a[1234567],w,x,y,z;
bool used[1234567];
vector<ll> v[1234567];
ll B[123][1234],S[123][1234],D[123][123],C[123][123],c1[123][123];
bool check(ll val){
rep(i,1,n){
rep(j,1,n){
C[i][j] = val * c1[i][j] - D[i][j];
}
}
rep(k,1,n){
rep(i,1,n){
rep(j,1,n){
C[i][j] = min(C[i][j], C[i][k] + C[k][j]);
}
}
}
rep(i,1,n)
if(C[i][i] <= 0)
return 1;
return 0;
}
int main(){
cin>>n>>m>>k;
rep(i,1,n){
rep(j,1,k){
cin>>x>>y;
B[i][j]=x;
S[i][j]=y;
}
}
rep(i,1,n){
rep(j,1,n)c1[i][j]=MAX;
}
while(m--){
cin>>x>>y>>z;
c1[x][y]=z;
}
rep(k,1,n){
rep(i,1,n){
rep(j,1,n){
c1[i][j]=min(c1[i][j] , c1[i][k] + c1[k][j]);
}
}
}
rep(i,1,n){
rep(j,1,n){
rep(o,1,k){
if(B[i][o] != -1 && S[j][o] != -1)
D[i][j] = max(D[i][j], S[j][o] - B[i][o]);
}
}
}
per(i,0,30){
if(check(ans + 1<<i)==1)ans+=(1<<i);
}
cout<<ans;
}
