#include <bits/stdc++.h>
using namespace std;
const int N = 100 + 10,
K = 1000 + 10;
const long long MAX = 1'000'000'000'000'000'000 + 10;
int n, m, k;
int buy[N][K], sell[N][K];
vector<pair<int, int>> ad[N];
long long dist[N][N], profit[N][N];
long long f[N][N];
int32_t main() {
cin.tie(0)->sync_with_stdio(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 = 1; i <= m; ++i) {
int u, v, w; cin >> u >> v >> w;
ad[u].push_back({v, w});
}
memset(dist, 14, sizeof dist);
for (int u = 1; u <= n; ++u) {
for (const auto& [v, w] : ad[u]) dist[u][v] = w;
}
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 x = 1; x <= k; ++x) {
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
if (buy[i][x] == -1 || sell[j][x] == -1) continue;
profit[i][j] = max(profit[i][j], 1ll * sell[j][x] - buy[i][x]);
}
}
}
auto chk = [&](int expectedValue) {
memset(f, -14, sizeof f);
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j)
if (i != j) f[i][j] = profit[i][j] - min(dist[i][j], MAX / expectedValue) * expectedValue;
}
for (int k = 1; k <= n; ++k) {
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) f[i][j] = max(f[i][j], f[i][k] + f[k][j]);
}
}
for (int i = 1; i <= n; ++i) if (f[i][i] >= 0) return true;
return false;
};
int le = 1, ri = 1'000'000'000, ret = 0;
while (le <= ri) {
int mid = (le + ri) >> 1;
if (chk(mid)) le = (ret = mid) + 1;
else ri = mid - 1;
}
cout << ret << "\n";
}
