//thatsramen
#include <bits/stdc++.h>
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define eb emplace_back
#define pb push_back
#define ft first
#define sd second
#define pi pair<int, int>
#define pll pair<ll, ll>
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define dbg(...) dbg_out(__VA_ARGS__)
using ll = long long;
using ld = long double;
using namespace std;
using namespace __gnu_pbds;
//Constants
const ll INF = 5 * 1e18;
const int IINF = 2 * 1e9;
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
const ld PI = 3.14159265359;
//Templates
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) {return os << '(' << p.first << ", " << p.second << ')';}
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) {os << '['; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << ']';}
void dbg_out() {cerr << endl;}
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cerr << H << ' '; dbg_out(T...); }
template<typename T> void mins(T& x, T y) {x = min(x, y);}
template<typename T> void maxs(T& x, T y) {x = max(x, y);}
template<typename T> using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using omset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
//order_of_key(k): number of elements strictly less than k
//find_by_order(k): k-th element in the set
void setPrec() {cout << fixed << setprecision(15);}
void unsyncIO() {cin.tie(0)->sync_with_stdio(0);}
void setIn(string s) {freopen(s.c_str(), "r", stdin);}
void setOut(string s) {freopen(s.c_str(), "w", stdout);}
void setIO(string s = "") {
unsyncIO(); setPrec();
if(s.size()) setIn(s + ".in"), setOut(s + ".out");
}
// #define TEST_CASES
const ll MAX = 2ll * 1000 * 1000 * 1000 * 1000 * 1000 * 1000;
void solve() {
int n, m, k;
cin >> n >> m >> k;
vector<vector<pll>> cost(n, vector<pll> (k));
for (int i = 0; i < n; i++) {
for (int j = 0; j < k; j++) {
cin >> cost[i][j].ft >> cost[i][j].sd;
}
}
vector<vector<ll>> dist(n, vector<ll> (n, MAX));
for (int i = 0; i < m; i++) {
int u, v; ll t;
cin >> u >> v >> t;
u--; v--;
dist[u][v] = t;
}
auto floyd = [&](vector<vector<ll>> &adj) {
for (int z = 0; z < n; z++) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
mins(adj[i][j], adj[i][z] + adj[z][j]);
}
}
}
};
floyd(dist);
vector<vector<ll>> prof(n, vector<ll> (n, 0));
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
for (int z = 0; z < k; z++) {
if (cost[i][z].ft == -1) continue;
if (cost[j][z].sd == -1) continue;
maxs(prof[i][j], cost[j][z].sd - cost[i][z].ft);
}
}
}
auto ok = [&](ll rat) -> bool {
vector<vector<ll>> adj(n, vector<ll> (n, MAX));
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
adj[i][j] = min(dist[i][j], MAX / rat) * rat - prof[i][j];
}
}
floyd(adj);
for (int i = 0; i < n; i++) {
if (adj[i][i] <= 0) return true;
}
return false;
};
ll ans = 0;
ll lo = 1, hi = 1ll * 1000 * 1000 * 1000 * 1000;
while (lo <= hi) {
ll mi = lo + (hi - lo) / 2;
if (ok(mi)) {
ans = mi;
lo = mi + 1;
} else {
hi = mi - 1;
}
}
cout << ans;
}
int main() {
setIO();
int tt = 1;
#ifdef TEST_CASES
cin >> tt;
#endif
while (tt--)
solve();
return 0;
}
