#include <bits/stdc++.h>
#define nl '\n'
#ifdef LOCAL
#include "template/debug.hpp"
#else
#define dbg(...) ;
#define timer(...) ;
#endif
signed main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int N, M, K;
std::cin >> N >> M >> K;
constexpr int64_t inf = 1e18;
int64_t B[N][K], S[N][K], d[N][N], p[N][N], cost[N][N];
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
d[i][j] = inf;
}
}
for (int i = 0; i < N; i++) {
for (int j = 0; j < K; j++) {
std::cin >> B[i][j] >> S[i][j];
}
}
for (int i = 0; i < M; i++) {
int u, v, c;
std::cin >> u >> v >> c;
--u, --v;
d[u][v] = std::min(d[u][v], (int64_t) c);
}
for (int k = 0; k < N; k++) {
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
d[i][j] = std::min(d[i][j], d[i][k] + d[k][j]);
}
}
}
dbg("done floyd")
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
p[i][j] = 0; // not doing shit
for (int k = 0; k < K; k++) {
if (B[i][k] != -1 && S[j][k] != -1) {
p[i][j] = std::max(p[i][j], S[j][k] - B[i][k]);
}
}
}
}
dbg("done profit");
int lb = 0, rb = 1e9;
while (lb < rb) {
int mb = (lb + rb + 1) / 2;
dbg(mb);
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
cost[i][j] = std::min(inf / mb, d[i][j]) * mb - p[i][j];
}
}
for (int k = 0; k < N; k++) {
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
cost[i][j] = std::min(cost[i][j], cost[i][k] + cost[k][j]);
}
}
}
bool good = 0;
for (int i = 0; i < N; i++) {
good |= cost[i][i] <= 0;
}
if (good) {
lb = mb;
} else {
rb = mb - 1;
}
}
std::cout << lb << nl;
// profit / time >= mid
// profit - time * mid >= 0
// a neg loop
}
