#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;
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
#define int long long
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define ppb pop_back
#define eb emplace_back
#define g0(a) get<0>(a)
#define g1(a) get<1>(a)
#define g2(a) get<2>(a)
#define g3(a) get<3>(a)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using db = double;
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using iii = tuple<int, int, int>;
using iiii = tuple<int, int, int, int>;
template<class key, class value = null_type, class cmp = less<key> >
using ordered_set = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;
int N, M, K, adj[105][105], B[105][1005], S[105][1005], m[105][105], V[9905], W[9905], T[9905];
db lo, hi, ans, adj2[105][105];
const db eps = 1e-9;
main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> N >> M >> K;
for (int i = 1; i <= N; i++)
for (int j = 1; j <= K; j++) cin >> B[i][j] >> S[i][j];
for (int i = 1; i <= N; i++)
for (int j = 1; j <= N; j++)
adj[i][j] = (i == j ? 0 : (int)1e16);
for (int i = 1; i <= M; i++) {
cin >> V[i] >> W[i] >> T[i];
adj[V[i]][W[i]] = min(adj[V[i]][W[i]], T[i]);
}
for (int k = 1; k <= N; k++)
for (int i = 1; i <= N; i++)
for (int j = 1; j <= N; j++)
adj[i][j] = min(adj[i][j], adj[i][k] + adj[k][j]);
for (int i = 1; i <= N; i++)
for (int j = 1; j <= N; j++) {
m[i][j] = 0;
for (int k = 1; k <= K; k++)
if (S[j][k] != -1 && B[i][k] != -1) m[i][j] = max(m[i][j], S[j][k] - B[i][k]);
}
hi = 1e16;
for (int run = 0; run < 200; run++) {
db mid = (lo + hi) / 2.;
bool can = 0;
for (int i = 1; i <= N; i++)
for (int j = 1; j <= N; j++)
adj2[i][j] = mid * (db)adj[i][j] - (db)m[i][j];
for (int k = 1; k <= N; k++)
for (int i = 1; i <= N; i++)
for (int j = 1; j <= N; j++)
adj2[i][j] = min(adj2[i][j], adj2[i][k] + adj2[k][j]);
for (int i = 1; i <= N; i++)
if (adj2[i][i] < 0.) can = 1;
if (can) ans = mid, lo = mid;
else hi = mid;
}
cout << (ceil(ans) - ans < eps ? ceil(ans) : floor(ans)) << '\n';
}
