#include <algorithm>
#include <iostream>
#include <iomanip>
#include <numeric>
#include <cassert>
#include <cstring>
#include <vector>
#include <stack>
#include <cmath>
typedef long long llong;
const int MAXN = 100 + 10;
const int MAXK = 1000 + 10;
const int INF = 2e9;
int n, m, k;
llong dist[MAXN][MAXN];
llong profit[MAXN][MAXN];
llong b[MAXN][MAXK];
llong s[MAXN][MAXK];
bool bl[MAXN][MAXN];
std::pair <llong,llong> dp[MAXN][MAXN];
std::pair <llong,llong> f(int start, int curr)
{
if (bl[start][curr])
{
return dp[start][curr];
}
bl[start][curr] = true;
dp[start][curr] = {0, 1};
assert(curr == start || dist[curr][start] != 1e18);
if (start != curr && dist[curr][start] != 1e18)
{
dp[start][curr] = {profit[curr][start], dist[curr][start]};
}
for (int i = 1 ; i <= n ; ++i)
{
if (i == start || i == curr || dist[curr][i] == 1e18 || dist[i][start] == 1e18) continue;
llong currP = f(start, i).first;
llong currQ = f(start, i).second;
if (double(dp[start][curr].first / dp[start][curr].second) < double((currP + profit[curr][i]) / (currQ + dist[curr][i])))
{
dp[start][curr].first = currP + profit[curr][i];
dp[start][curr].second = currQ + dist[curr][i];
}
}
return dp[start][curr];
}
void solve()
{
for (int mid = 1 ; mid <= n ; ++mid)
{
for (int i = 1 ; i <= n ; ++i)
{
for (int j = 1 ; j <= n ; ++j)
{
if (i == j || i == mid || j == mid) continue;
dist[i][j] = std::min(dist[i][j], dist[i][mid] + dist[mid][j]);
}
}
}
for (int i = 1 ; i <= n ; ++i)
{
for (int j = 1 ; j <= n ; ++j)
{
if (i == j) continue;
for (int item = 1 ; item <= k ; ++item)
{
if (b[i][item] == -1 || s[j][item] == -1) continue;
profit[i][j] = std::max(profit[i][j], s[j][item] - b[i][item]);
}
}
}
llong p = 0, q = 1;
for (int i = 1 ; i <= n ; ++i)
{
llong currP = f(i, i).first;
llong currQ = f(i, i).second;
if (p / q < currP / currQ)
{
p = currP;
q = currQ;
}
}
std::cout << p / q << '\n';
}
void read()
{
std::cin >> n >> m >> k;
for (int i = 1 ; i <= n ; ++i)
{
for (int j = 1 ; j <= k ; ++j)
{
std::cin >> b[i][j] >> s[i][j];
}
}
for (int i = 1 ; i <= n ; ++i)
{
for (int j = 1 ; j <= n ; ++j)
{
dist[i][j] = 1e18;
}
}
for (int i = 1 ; i <= m ; ++i)
{
int x, y, d;
std::cin >> x >> y >> d;
dist[x][y] = d;
}
}
void fastIO()
{
std::ios_base :: sync_with_stdio(0);
std::cout.tie(nullptr);
std::cin.tie(nullptr);
}
int main()
{
fastIO();
read();
solve();
return 0;
}
/*
4 5 2
10 9 5 2
6 4 20 15
9 7 10 9
-1 -1 16 11
1 2 3
2 3 3
1 4 1
4 3 1
3 1 1
*/
