#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
using ull = unsigned long long;
using ll = long long;
using namespace std;
constexpr ll INF = (ll) 1e18;
int main() {
#ifdef HOME
ifstream cin("input.in");
ofstream cout("output.out");
#endif
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
int n, m, k;
cin >> n >> m >> k;
vector<vector<int>> buy(n + 1, vector<int>(k + 1));
vector<vector<int>> sell(n + 1, vector<int>(k + 1));
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= k; j++) {
cin >> buy[i][j] >> sell[i][j];
}
}
vector<vector<ll>> travel_time(n + 1, vector<ll>(n + 1, INF));
for (int i = 1; i <= n; i++) {
travel_time[i][i] = 0;
}
while (m--) {
int x, y, t;
cin >> x >> y >> t;
travel_time[x][y] = t;
}
for (int z = 1; z <= n; z++) {
auto temp = travel_time;
for (int x = 1; x <= n; x++) {
for (int y = 1; y <= n; y++) {
temp[x][y] = min(temp[x][y], travel_time[x][z] + travel_time[z][y]);
}
}
travel_time = move(temp);
}
vector<vector<ll>> best_profit(n + 1, vector<ll>(n + 1));
for (int x = 1; x <= n; x++) {
for (int y = 1; y <= n; y++) {
for (int item = 1; item <= k; item++) {
if (buy[x][item] != -1 && sell[y][item] != -1) {
best_profit[x][y] = max(best_profit[x][y], 1LL * sell[y][item] - buy[x][item]);
}
}
}
}
auto Check = [&](ll coef) {
vector<vector<ll>> dp(n + 1, vector<ll>(n + 1, -INF));
for (int x = 1; x <= n; x++) {
for (int y = 1; y <= n; y++) {
if (x != y) {
dp[x][y] = best_profit[x][y] - travel_time[x][y] * coef;
}
}
}
for (int z = 1; z <= n; z++) {
auto temp = dp;
for (int x = 1; x <= n; x++) {
for (int y = 1; y <= n; y++) {
temp[x][y] = max(temp[x][y], dp[x][z] + dp[z][y]);
}
}
dp = move(temp);
}
for (int i = 1; i <= n; i++) {
if (dp[i][i] >= 0) {
return false;
}
}
return true;
};
ll result = (1LL << 31);
for (int step = 1 << 30; step; step >>= 1) {
if (result >= step && Check(result - step)) {
result -= step;
}
}
cout << result - 1;
return 0;
}
