#include <iostream>
#include <iomanip>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <cassert>
#include <string>
#include <set>
#include <map>
#include <random>
#include <bitset>
#include <string>
#include <unordered_set>
#include <unordered_map>
#include <deque>
#include <queue>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
using namespace std;
using ll = long long;
using ul = unsigned long long;
using ld = long double;
const int N = 101, K = 1001;
ll inf = 1e15;
ll md[N][N], mx[N][N], b[N][K], s[N][K], g[N][N];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
ll n, m, k, u, v, w;
cin >> n >> m >> k;
rep(i, n)
rep(j, k) {
cin >> b[i][j] >> s[i][j];
if (b[i][j] < 0)
b[i][j] = inf;
}
rep(i, n)
rep(j, n) {
md[i][j] = inf;
rep(l, k)
mx[i][j] = max(mx[i][j], s[j][l] - b[i][l]);
}
rep(i, m) {
cin >> u >> v >> w;
u--; v--;
md[u][v] = min(md[u][v], w);
}
rep(i, n)
rep(j, n)
rep(l, n)
md[j][l] = min(md[j][l], md[j][i] + md[i][l]);
ll cl = 0, cr = 1e9, cm;
while (cr - cl > 1) {
cm = (cl + cr) / 2;
rep(i, n)
rep(j, n) {
if (i == j || md[i][j] == inf)
g[i][j] = -inf;
else
g[i][j] = mx[i][j] - cm * md[i][j];
}
rep(i, n)
rep(j, n)
rep(l, n)
g[j][l] = max(g[j][l], g[j][i] + g[i][l]);
rep(i, n)
if (g[i][i] >= 0)
cl = cm;
if (cl != cm)
cr = cm;
}
cout << cl;
}
