#include <iostream>
#include <vector>
#include <algorithm>
#include <random>
#include <set>
#include <map>
#include <queue>
#include <cstring>
#include <cmath>
#include <bitset>
#include <iomanip>
#include <functional>
//#include <unordered_map>
using namespace std;
template<typename T> void uin(T &a, T b) {if (b < a) a = b;}
template<typename T> void uax(T &a, T b) {if (b > a) a = b;}
#define int long long
#define double long double
#define left left228
#define right right228
#define mp make_pair
#define all(v) v.begin(), v.end()
const int N = 105, K = 1005;
const double eps = 1e-6;
const int INF = 1e18 + 228;
int n, m, k;
int buy[N][K], sell[N][K];
vector< pair<int, int> > g[N];
int dist[N][N];
int max_profit[N][N];
void pre() {
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
dist[i][j] = INF;
}
dist[i][i] = 0;
}
for (int v = 1; v <= n; ++v) {
for (pair<int, int> go : g[v]) {
int to = go.first;
int w = go.second;
uin(dist[v][to], w);
}
}
for (int k = 1; k <= n; ++k) {
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
if (dist[i][k] < INF && dist[k][j] < INF) {
uin(dist[i][j], dist[i][k] + dist[k][j]);
}
}
}
}
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
for (int t = 1; t <= k; ++t) {
if (buy[i][t] != -1 && sell[j][t] != -1) {
uax(max_profit[i][j], sell[j][t] - buy[i][t]);
}
}
}
}
}
double d[N], d2[N];
bool Gr(double x, double y) {
return x > y + eps;
}
struct edge
{
int from, to;
double w;
edge() {}
edge(int _from, int _to, double _w) {
from = _from;
to = _to;
w = _w;
}
};
bool check(double x) {
vector< edge > edges;
for (int a = 1; a <= n; ++a) {
for (int b = 1; b <= n; ++b) {
if (dist[a][b] < INF) {
double weight = (double)max_profit[a][b] - (double)dist[a][b] * x;
edges.emplace_back( a, b, min((double)INF, -weight) );
}
}
}
for (int i = 1; i <= n; ++i) {
d[i] = INF;
}
d[1] = 0;
int V = -1;
for (int it = 0; it < n; ++it) {
V = -1;
for (auto e : edges) {
if (d[ e.from ] + e.w + eps < d[e.to]) {
d[e.to] = d[e.from] + e.w;
V = e.to;
}
}
}
if (V == -1) return 0;
return 1;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n >> m >> k;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= k; ++j) {
cin >> buy[i][j] >> sell[i][j];
}
}
for (int i = 0; i < m; ++i) {
int u, v, w;
cin >> u >> v >> w;
g[u].emplace_back(v, w);
}
pre();
double l = 0, r = 1e10;
for (int i = 0; i < 100; ++i) {
if (abs(r - l) <= eps) break;
double M = (l + r) / 2.0;
if (check(M)) {
l = M;
} else {
r = M;
}
}
cout << setprecision(15) << (int)r << '\n';
return 0;
}
/*
*/
