#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 100 + 7;
const int K = 1000 + 7;
const int INF = (int) 1e18;
int dist[N][N];
int n, m, k, buy[N][K], sell[N][K], best[N], tab[N][N], sol[N][N];
bool ok(int coef) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
sol[i][j] = -INF;
if (dist[i][j] == INF) continue;
int mx = tab[i][j];
sol[i][j] = mx - coef * dist[i][j];
}
}
for (int k = 1; k <= n; k++) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
sol[i][j] = max(sol[i][j], sol[i][k] + sol[k][j]);
sol[i][j] = min(sol[i][j], INF);
}
}
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (sol[i][j] + sol[j][i] >= 0) {
return 1;
}
}
}
return 0;
}
signed main() {
ios::sync_with_stdio(0); cin.tie(0);
///freopen ("input", "r", stdin);
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 = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
dist[i][j] = INF;
}
}
for (int i = 1; i <= m; i++) {
int a, b, c;
cin >> a >> b >> c;
dist[a][b] = c;
}
for (int k = 1; k <= n; k++) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
dist[i][j] = min(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 item = 1; item <= k; item++) {
/// buy at i, sell at j
if (buy[i][item] != -1 && sell[j][item] != -1) {
tab[i][j] = max(tab[i][j], sell[j][item] - buy[i][item]);
}
}
}
}
int l = 1, r = (int) 1e9, sol = 0;
while (l <= r) {
int m = (l + r) / 2;
if (ok(m)) {
sol = m;
l = m + 1;
} else {
r = m - 1;
}
}
assert(!ok(sol + 1));
cout << sol << "\n";
return 0;
}
