#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define endl '\n'
#define fi first
#define se second
#define For(i, l, r) for (int i = l; i < r; i++)
#define ForE(i, l, r) for (int i = l; i <= r; i++)
#define FordE(i, l, r) for (int i = l; i >= r; i--)
#define Fora(v, a) for (auto v: a)
#define bend(a) a.begin(), a.end()
#define isz(a) ((signed)a.size())
typedef long long ll;
typedef long double ld;
typedef pair <int, int> pii;
typedef vector <int> vi;
typedef vector <pii> vpii;
typedef vector <vi> vvi;
const int N = 1e2 + 5, K = 1e3 + 5, inf = 1e9 + 7;
const ll infll = (ld)1e18 + 7;
int n, m, k;
int b[N][K], s[N][K];
ll adj[N][N];
ll dist[N][N];
void floyd_warshall(){
ForE(k, 1, n){
ForE(i, 1, n){
ForE(j, 1, n){
if (dist[i][j] > dist[i][k] + dist[k][j]){
dist[i][j] = dist[i][k] + dist[k][j];
}
}
}
}
}
ll profit[N][N];
signed main(){
// ios_base::sync_with_stdio(0);
// cin.tie(0); cout.tie(0);
// freopen("KEK.inp", "r", stdin);
// freopen("KEK.out", "w", stdout);
cin >> n >> m >> k;
ForE(i, 1, n){
ForE(j, 1, k){
cin >> b[i][j] >> s[i][j];
}
}
ForE(i, 1, n){
ForE(j, 1, n){
adj[i][j] = infll;
}
}
ForE(i, 1, m){
int u, v, w; cin >> u >> v >> w;
adj[u][v] = w;
}
ForE(i, 1, n){
ForE(j, 1, n){
dist[i][j] = adj[i][j];
}
}
floyd_warshall();
ForE(i, 1, n){
ForE(j, 1, n){
adj[i][j] = dist[i][j];
}
}
ForE(i, 1, n){
ForE(j, 1, n){
ForE(kk, 1, k){
if (b[i][kk] != -1 and s[j][kk] != -1){
profit[i][j] += max(0, s[j][kk] - b[i][kk]);
}
}
}
}
int lo = 0, hi = inf;
while (lo < hi){
int mid = (lo + hi + 1) >> 1;
ForE(i, 1, n){
ForE(j, 1, n){
dist[i][j] = (ll)mid * min(adj[i][j], infll / mid) - profit[i][j];
}
}
floyd_warshall();
bool ck = 0;
ForE(i, 1, n){
if (dist[i][i] <= 0){
ck = 1;
}
}
if (ck){
lo = mid;
}
else{
hi = mid - 1;
}
}
cout << lo << endl;
}
/*
==================================================+
INPUT: |
--------------------------------------------------|
--------------------------------------------------|
==================================================+
OUTPUT: |
--------------------------------------------------|
--------------------------------------------------|
==================================================+
*/
