#include<bits/stdc++.h>
#define god dimasi5eks
#pragma GCC optimize("O3")
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define mod 1000000007
#define dancila 3.14159265359
#define eps 1e-9
// #define fisier 1
using namespace std;
typedef long long ll;
int n, m, k, buy[102][1002], sell[102][1002], rf[102][102];
int main()
{
#ifdef fisier
ifstream f("input.in");
ofstream g("output.out");
#endif
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m >> k;
for(int i = 1; i <= n; ++i)
{
for(int j = 1; j <= k; ++j)
cin >> buy[i][j] >> sell[i][j];
}
for(int i = 1; i <= m; ++i)
{
int a, b, c;
cin >> a >> b >> c;
rf[a][b] = c;
}
for(int k = 1; k <= n; ++k)
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
if(i != j && rf[i][k] && rf[k][j])
{
if(rf[i][j] == 0 || rf[i][j] > rf[i][k] + rf[k][j])
rf[i][j] = rf[i][k] + rf[k][j];
}
int ans = 0;
for(int start = 1; start <= n; ++start)
{
int states = 1000000 / (n * k);
deque<pair<int, pair<int, int> > >d;
d.pb({start, {0, 0}});
while(!d.empty())
{
--states;
pair<int, pair<int, int> > nod = d[0];
// cout << nod.fi << " " << nod.se.fi << " " << nod.se.se << '\n';
d.pop_front();
for(int vec = 1; vec <= n; ++vec)
{
if(vec != nod.fi && rf[nod.fi][vec])
{
for(int j = 1; j <= k; ++j)
if(buy[nod.fi][j] != -1 && sell[vec][j] != -1 && buy[nod.fi][j] < sell[vec][j])
{
if(vec == start)
{
// cout << nod.fi << " " << vec << " " << (nod.se.fi + sell[vec][j] - buy[nod.fi][j]) << " " << (nod.se.se + rf[nod.fi][vec]) << '\n';
ans = max(ans, (nod.se.fi + sell[vec][j] - buy[nod.fi][j]) / (nod.se.se + rf[nod.fi][vec]));
}
else
d.pb({vec, {nod.se.fi + sell[vec][j] - buy[nod.fi][j], nod.se.se + rf[nod.fi][vec]}});
}
if(vec == start)
{
// cout << nod.fi << " " << vec << " " << (nod.se.fi) << " " << (nod.se.se + rf[nod.fi][vec]) << '\n';
ans = max(ans, (nod.se.fi) / (nod.se.se + rf[nod.fi][vec]));
}
else
d.pb({vec, {nod.se.fi, nod.se.se + rf[nod.fi][vec]}});
}
}
if(states == 0)
break;
}
}
cout << ans;
return 0;
}
