#include <iostream>
#include <vector>
#include <tuple>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <map>
#include <cmath>
#include <random>
#include <string>
#include <bitset>
#include <cassert>
#include <climits>
#include <algorithm>
#include <unordered_set>
#include <unordered_map>
using namespace std;
#define ll long long
#define f first
#define s second
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template<typename A> void __print(const A &x);
template<typename A, typename B> void __print(const pair<A, B> &p);
template<typename... A> void __print(const tuple<A...> &t);
template<typename T> void __print(stack<T> s);
template<typename T> void __print(queue<T> q);
template<typename T, typename... U> void __print(priority_queue<T, U...> q);
template<typename A> void __print(const A &x) {
bool first = true;
cerr << '{';
for (const auto &i : x) {
cerr << (first ? "" : ","), __print(i);
first = false;
}
cerr << '}';
}
template<typename A, typename B> void __print(const pair<A, B> &p) {
cerr << '(';
__print(p.f);
cerr << ',';
__print(p.s);
cerr << ')';
}
template<typename... A> void __print(const tuple<A...> &t) {
bool first = true;
cerr << '(';
apply([&first] (const auto &...args) { ((cerr << (first ? "" : ","), __print(args), first = false), ...); }, t);
cerr << ')';
}
template<typename T> void __print(stack<T> s) {
vector<T> debugVector;
while (!s.empty()) {
T t = s.top();
debugVector.push_back(t);
s.pop();
}
reverse(debugVector.begin(), debugVector.end());
__print(debugVector);
}
template<typename T> void __print(queue<T> q) {
vector<T> debugVector;
while (!q.empty()) {
T t = q.front();
debugVector.push_back(t);
q.pop();
}
__print(debugVector);
}
template<typename T, typename... U> void __print(priority_queue<T, U...> q) {
vector<T> debugVector;
while (!q.empty()) {
T t = q.top();
debugVector.push_back(t);
q.pop();
}
__print(debugVector);
}
void _print() { cerr << "]\n"; }
template <typename Head, typename... Tail> void _print(const Head &H, const Tail &...T) {
__print(H);
if (sizeof...(T)) cerr << ", ";
_print(T...);
}
#ifdef DEBUG
#define D(...) cerr << "Line: " << __LINE__ << " [" << #__VA_ARGS__ << "] = ["; _print(__VA_ARGS__)
#else
#define D(...)
#endif
int n, m, k;
ll b[105][1005], s[105][1005], t[105][105], p[105][105], g[105][105], lf, rh, md;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n >> m >> k;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= k; j++) {
cin >> b[i][j] >> s[i][j];
}
}
fill(&t[0][0], &t[0][0] + sizeof(t) / sizeof(t[0][0]), 1e18);
for (int i = 0, a, x, c; i < m; i++) {
cin >> a >> x >> c;
t[a][x] = c;
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
for (int a = 1; a <= n; a++) {
t[j][a] = min(t[j][a], t[j][i] + t[i][a]);
}
for (int a = 1; a <= k; a++) {
if (b[i][a] != -1 && s[j][a] != -1) {
p[i][j] = max(p[i][j], s[j][a] - b[i][a]);
}
}
}
}
lf = 1, rh = 1e9;
while (lf <= rh) {
md = (lf + rh) / 2;
fill(&g[0][0], &g[0][0] + sizeof(g) / sizeof(g[0][0]), 1e18 / md);
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
g[i][j] = md * t[i][j] - p[i][j];
}
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
for (int a = 1; a <= n; a++) {
g[j][a] = min(g[j][a], g[j][i] + g[i][a]);
}
}
}
bool good = false;
for (int i = 1; i <= n; i++) {
if (g[i][i] <= 0) {
good = true;
}
}
if (good) lf = md + 1;
else rh = md - 1;
}
cout << rh << "\n";
}
