#include <bits/stdc++.h>
#define int long long
using namespace std;
const int INF = 2e18L;
void maxSelf(int &x, int y) {
if (x < y) {
x = y;
}
}
void minSelf(int &x, int y) {
if (y < x) {
x = y;
}
}
void FloydWarshall(vector<vector<int>> &d) {
int n = d.size() - 1;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
for (int k = 1; k <= n; ++k) {
minSelf(d[i][j], d[i][k] + d[k][j]);
}
}
}
}
void testCase() {
int n, m, k;
cin >> n >> m >> k;
vector<vector<int>> b(n + 1, vector<int>(k + 1)), s(n + 1, vector<int>(k + 1));
vector<vector<int>> d(n + 1, vector<int>(n + 1, INF));
for (int u = 1; u <= n; ++u) {
for (int i = 1; i <= k; ++i) {
cin >> b[u][i] >> s[u][i];
}
}
for (int i = 0; i < m; ++i) {
int u, v, w;
cin >> u >> v >> w;
d[u][v] = w;
}
FloydWarshall(d);
vector<vector<int>> profit(n + 1, vector<int>(n + 1));
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
for (int p = 1; p <= k; ++p) {
if (b[i][p] != -1 && s[j][p] != -1) {
maxSelf(profit[i][j], s[j][p] - b[i][p]);
}
}
}
}
int l = 1, r = 1e9;
while (l <= r) {
int mid = (l + r) / 2;
vector<vector<int>> dp(n + 1, vector<int>(n + 1));
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
dp[i][j] = (int)mid * min(d[i][j], INF / mid) - profit[i][j];
}
}
FloydWarshall(dp);
bool ok = false;
for (int v = 1; v <= n; ++v) {
if (dp[v][v] <= 0) {
ok = true;
}
}
if (ok) {
l = mid + 1;
} else {
r = mid - 1;
}
}
cout << r << '\n';
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int tests = 1;
for (int tc = 0; tc < tests; ++tc) {
testCase();
}
return 0;
}
