#include <bits/stdc++.h>
using i64 = long long;
constexpr int inf32 = 1 << 30;
constexpr i64 inf = 1ll << 50;
void calcMinDist(std::vector<std::vector<i64>> &graph) {
const int n = (int)graph.size();
for (int k = 0; k < n; ++k) {
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
graph[i][j] = std::min(graph[i][j], graph[i][k] + graph[k][j]);
}
}
}
}
void calcMaxDist(std::vector<std::vector<i64>> &graph) {
const int n = (int)graph.size();
for (int k = 0; k < n; ++k) {
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
graph[i][j] = std::max(graph[i][j], graph[i][k] + graph[k][j]);
graph[i][j] = std::min(graph[i][j], inf / 10);
}
}
}
}
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int N, M, K;
std::cin >> N >> M >> K;
std::vector<std::vector<i64>> buyList(N, std::vector<i64>(K)), sellList(N, std::vector<i64>(K));
for (int i = 0; i < N; ++i) {
for (int j = 0; j < K; ++j) {
std::cin >> buyList[i][j] >> sellList[i][j];
}
}
std::vector<std::vector<i64>> baseGraph(N, std::vector<i64>(N, inf32));
for (int i = 0; i < M; ++i) {
int v, w;
i64 t;
std::cin >> v >> w >> t;
--v, --w;
baseGraph[v][w] = t;
}
calcMinDist(baseGraph);
std::vector<std::vector<i64>> profitList(N, std::vector<i64>(N));
for (int i = 0; i < N; ++i) {
for (int j = 0; j < N; ++j) {
i64 ma = 0;
for (int k = 0; k < K; ++k) {
if (buyList[i][k] == -1 or sellList[j][k] == -1) {
continue;
}
ma = std::max(ma, sellList[j][k] - buyList[i][k]);
}
profitList[i][j] = ma;
}
}
i64 ok = 0, ng = inf32;
while (ng - ok > 1) {
const auto mid = (ok + ng) / 2;
std::vector<std::vector<i64>> realGraph(N, std::vector<i64>(N));
for (int i = 0; i < N; ++i) {
for (int j = 0; j < N; ++j) {
realGraph[i][j] = (profitList[i][j] - mid * baseGraph[i][j]);
realGraph[i][j] = std::max(realGraph[i][j], -inf);
}
}
for (int i = 0; i < N; ++i) {
realGraph[i][i] = -inf;
}
calcMaxDist(realGraph);
bool isOk = false;
for (int i = 0; i < N; ++i) {
if (realGraph[i][i] >= 0) {
isOk = true;
}
}
if (isOk) {
ok = mid;
} else {
ng = mid;
}
}
std::cout << ok << std::endl;
}
