#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 maxdif[102][102];
ll bst[102], bst2[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];
}
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
if(i != j && rf[i][j])
for(int x = 1; x <= k; ++x)
if(i != j && rf[i][j] && buy[i][x] != -1 && sell[j][x] != -1)
maxdif[i][j] = max(maxdif[i][j], sell[j][x] - buy[i][x]);
ll ans = 0;
int dif = 0;
for(int start = 1; start <= n; ++start)
{
int states = dif + 500000 / n;
deque<pair<int, pair<ll, ll> > >d;
memset(bst, 0, sizeof(bst));
memset(bst2, 0, sizeof(bst2));
d.pb({start, {0, 0}});
while(!d.empty())
{
pair<int, pair<ll, ll> > nod = d[0];
d.pop_front();
if(bst[nod.fi] == 0 && nod.se.fi)
bst[nod.fi] = nod.se.fi, bst2[nod.fi] = nod.se.se;
else
if(nod.se.fi * bst2[nod.fi] > nod.se.se * bst[nod.fi])
bst[nod.fi] = nod.se.fi, bst2[nod.fi] = nod.se.se;
else
if(nod.se.se > bst2[nod.fi])
continue;
--states;
for(int vec = 1; vec <= n; ++vec)
{
if(rf[nod.fi][vec])
{
if(vec == start)
{
ll rap = (nod.se.fi + maxdif[nod.fi][vec]) / (nod.se.se + rf[nod.fi][vec]);
ans = max(ans, rap);
}
else
d.pb({vec, {nod.se.fi + maxdif[nod.fi][vec], nod.se.se + rf[nod.fi][vec]}});
}
}
if(states == 0)
break;
}
dif = states;
}
cout << ans;
return 0;
}
