#include <bits/stdc++.h>
#define all(i) (i).begin(), (i).end()
#define debug(x) cerr << "Line(" << __LINE__ << ") -> " << #x << " is " << x << endl
using namespace std;
template<typename T1, typename T2>
ostream& operator << (ostream &i, pair<T1, T2> j) {
return i << j.first << ' ' << j.second;
}
template<typename T>
ostream& operator << (ostream &i, vector<T> j) {
i << '{' << j.size() << ':';
for (T ii : j) i << ' ' << ii;
return i << '}';
}
typedef long long ll;
typedef pair<int, int> pi;
const int inf = 1e9 + 1;
signed main() {
ios::sync_with_stdio(0), cin.tie(0);
int n, m, k;
cin >> n >> m >> k;
vector<vector<int>> b(n, vector<int>(k)), s(n, vector<int>(k));
for (int i = 0; i < n; ++i) for (int j = 0; j < k; ++j)
cin >> b[i][j] >> s[i][j];
vector<vector<int>> dis(n, vector<int>(n, inf));
for (int i = 0; i < n; ++i) dis[i][i] = 0;
for (int i = 0; i < m; ++i) {
int x, y, z;
cin >> x >> y >> z;
dis[x - 1][y - 1] = z;
}
for (int ii = 0; ii < n; ++ii) for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j)
dis[i][j] = min(dis[i][j], dis[i][ii] + dis[ii][j]);
vector<vector<int>> v(n, vector<int>(n, 0));
for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j) for (int ii = 0; ii < k; ++ii)
if (~s[j][ii] && ~b[i][ii]) v[i][j] = max(v[i][j], s[j][ii] - b[i][ii]);
int l = 0, r = inf;
vector<vector<ll>> tmp(n, vector<ll>(n));
while (l < r - 1) {
int mid = l + r >> 1;
for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j)
tmp[i][j] = v[i][j] - 1ll * mid * dis[i][j];
bool ok = false;
for (int ii = 0; ii < n; ++ii) for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j) if (dis[i][ii] < inf && dis[ii][j] < inf) {
if (i == j && i != ii && tmp[i][ii] + tmp[ii][j] >= 0) {
ok = true;
goto out;
}
tmp[i][j] = max(tmp[i][j], tmp[i][ii] + tmp[ii][j]);
}
out:
if (ok) l = mid;
else r = mid;
}
cout << l;
}
/*
* 0<x<1e9, 0<=ans<=1e9
* y/x >= k ? y-kx >= 0
*
* nm all dis
* logC
* n^2 v[i][j] = max(s[j][ii] - b[i][ii], all ii) - ans * dis[i][j]
* n^3 po-cycle
*
*/
