#include <bits/stdc++.h>
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
*/
using namespace std;
// using namespace __gnu_pbds;
using namespace chrono;
// mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());
/*
template <class T> using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;
*/
//***************** CONSTANTS *****************
const int64_t INF = 10'000'000'000'000'000;
const int MXN = 100;
const int MXK = 1000;
//***************** GLOBAL VARIABLES *****************
int N, M, K;
int64_t buy[MXN][MXK], sell[MXN][MXK], profit[MXN][MXN], dist[MXN][MXN];
//***************** AUXILIARY STRUCTS *****************
//***************** MAIN BODY *****************
bool check(int x){
int64_t adj[MXN][MXN];
for(int u = 0; u < N; u++)
for(int v = 0; v < N; v++)
adj[u][v] = profit[u][v] - dist[u][v] * x;
for(int k = 0; k < N; k++)
for(int i = 0; i < N; i++)
for(int j = 0; j < N; j++)
adj[i][j] = max(adj[i][j], adj[i][k] + adj[k][j]);
for(int i = 0; i < N; i++)
if(adj[i][i] >= 0)
return true;
return false;
}
void solve(){
cin >> N >> M >> K;
for(int i = 0; i < N; i++)
for(int j = 0; j < K; j++){
cin >> buy[i][j] >> sell[i][j];
if(buy[i][j] == -1) buy[i][j] = INF;
if(sell[i][j] == -1) sell[i][j] = -INF;
}
for(int i = 0; i < N; i++)
for(int j = 0; j < N; j++){
profit[i][j] = 0;
dist[i][j] = INF;
}
for(int i = 0; i < M; i++){
int u, v;
cin >> u >> v;
--u, --v;
cin >> dist[u][v];
}
for(int k = 0; k < N; k++)
for(int i = 0; i < N; i++)
for(int j = 0; j < N; j++)
dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
for(int i = 0; i < K; i++)
for(int u = 0; u < N; u++)
for(int v = 0; v < N; v++)
profit[u][v] = max(profit[u][v], sell[v][i] - buy[u][i]);
int l = 1, r = 1'000'000'000, ans = 0;
while(l <= r){
int mid = (l + r + 1) >> 1;
if(check(mid)){
l = mid + 1;
ans = mid;
}
else r = mid - 1;
}
cout << ans << '\n';
}
//***************** *****************
int32_t main(){
ios_base::sync_with_stdio(NULL);
cin.tie(NULL);
#ifdef LOCAL
auto begin = high_resolution_clock::now();
#endif
int tc = 1;
// cin >> tc;
for (int t = 0; t < tc; t++)
solve();
#ifdef LOCAL
auto end = high_resolution_clock::now();
cout << fixed << setprecision(4);
cout << "Execution Time: " << duration_cast<duration<double>>(end - begin).count() << "seconds" << endl;
#endif
return 0;
}
