#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define TASK ""
#define bit(x) (1LL << (x))
#define getbit(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
using namespace std;
template <typename T1, typename T2> bool mini(T1 &a, T2 b) {
if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maxi(T1 &a, T2 b) {
if (a < b) {a = b; return true;} return false;
}
mt19937_64 rd(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r) {
return l + rd() % (r - l + 1);
}
const int N = 105;
const int K = 1005;
const int oo = 1e9;
const long long ooo = 1e18;
const int mod = 1e9 + 7; // 998244353;
const long double pi = acos(-1);
long long cost[N][N];
long long dis[N];
int prof[N][N];
int d[N][N];
int b[N][K];
int s[N][K];
int cnt[N];
int n,m,k;
bool inq[N];
bool solve(int x) {
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
cost[i][j] = -ooo;
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++) if (d[i][j] < oo)
for (int k = 1; k <= n; k++) if (d[j][k] < oo) {
// cerr << i << " " << j << " " << k << "\n";
// cerr << prof[j][k] << "\n";
// cerr << d[i][j] << " " << d[j][k] << "\n";
maxi(cost[i][k], prof[j][k] - 1LL * (d[i][j] + d[j][k]) * x);
}
// for (int i = 1; i <= n; i++)
// for (int j = 1; j <= n; j++)
// cerr << i << " " << j << " " << cost[i][j] << "\n";
queue <int> q;
for (int i = 1; i <= n; i++) {
q.push(i);
dis[i] = 0;
}
for (int rep = 0; rep < n; rep++) {
bool neg = false;
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
neg |= maxi(dis[j], dis[i] + cost[i][j]);
if (rep == n - 1 && neg)
return true;
}
return false;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
#ifdef ONLINE_JUDGE
// freopen(TASK".inp","r",stdin);
// freopen(TASK".out","w",stdout);
#endif
cin >> n >> m >> k;
for (int i = 1; i <= n; i++)
for (int j = 1; j <= k; j++)
cin >> b[i][j] >> s[i][j];
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
if (i != j)
d[i][j] = oo;
for (int i = 1; i <= m; i++) {
int u,v,w;
cin >> u >> v >> w;
mini(d[u][v], w);
mini(d[v][u], w);
}
for (int j = 1; j <= n; j++)
for (int i = 1; i <= n; i++)
for (int k = 1; k <= n; k++)
mini(d[i][k], d[i][j] + d[j][k]);
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
for (int it = 1; it <= k; it++)
if (s[j][it] != -1 && b[i][it] != -1)
maxi(prof[i][j], s[j][it] - b[i][it]);
int lo = 0;
int hi = oo + 1;
while (hi - lo > 1) {
int mid = (lo + hi) >> 1;
if (solve(mid))
lo = mid;
else
hi = mid;
}
cout << lo;
return 0;
}
