#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#pragma GCC optimize("-Ofast")
//#pragma GCC optimize("trapv")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.2,popcnt,abm,mmx,avx2,tune=native")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-funroll-loops")
using namespace std;
using namespace __gnu_pbds;
#define vi vector<int>
#define vii vector<pair<int, int>>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define loop(_) for (int __ = 0; __ < (_); ++__)
#define forn(i, n) for (int i = 0; i < n; ++i)
#define pb push_back
#define f first
#define s second
#define sz(_) ((int)_.size())
#define all(_) _.begin(), _.end()
#define uni(_) unique(_)
#define lb lower_bound
#define ub upper_bound
#define si set<int>
#define ms multiset<int>
#define qi queue<int>
#define pq prioriry_queue<int>
using ll = long long;
using ld = long double;
const int N = 1e2 + 7;
const ll mod = 1e9 + 7;
const ll inf = 2e18;
auto ra = [] {char *p = new char ; delete p ; return ll(p) ; };
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count() * (ra() | 1));
typedef tree<pii, null_type, less<pii>, rb_tree_tag, tree_order_statistics_node_update> os;
int n, m, k;
vector<pair<ll, ll>> mrs[N];
ll cost[N][N];
ll d[N][N];
ll g[N][N];
bool check(ll mid)
{
for (int i = 0; i < n; ++i)
{
for (int j = 0; j < n; ++j)
{
if (d[i][j] < 1e15)
g[i][j] = cost[i][j] - d[i][j] * mid;
else
g[i][j] = -1e15;
}
}
for (int k = 0; k < n; ++k)
for (int i = 0; i < n; ++i)
for (int j = 0; j < n; ++j)
g[i][j] = max(g[i][j], g[i][k] + g[k][j]);
for (int i = 0; i < n; ++i)
if (g[i][i] >= 0)
return 1;
return 0;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("in.in", "r", stdin);
cin >> n >> m >> k;
for (int i = 0; i < n; ++i)
{
for (int j = 0; j < k; ++j)
{
pii v;
cin >> v.f >> v.s;
mrs[i].pb(v);
}
}
for (int i = 0; i < n; ++i)
fill(d[i], d[i] + N, 1e15);
for (int i = 0; i < m; ++i)
{
int u, v, w;
cin >> u >> v >> w;
--u;
--v;
d[u][v] = d[v][u] = min(d[u][v], 1ll * w);
}
for (int k = 0; k < n; ++k)
{
for (int i = 0; i < n; ++i)
{
for (int j = 0; j < n; ++j)
{
d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
}
}
}
for (int i = 0; i < n; ++i)
fill(cost[i], cost[i] + N, -1e15);
for (int i = 0; i < n; ++i)
{
for (int j = 0; j < n; ++j)
{
for (int r = 0; r < k; ++r)
{
if (~mrs[i][r].f && ~mrs[j][r].s)
cost[i][j] = max(cost[i][j], mrs[j][r].s - mrs[i][r].f);
}
}
}
ll lo = 0, hi = 1e9;
ll ans = 0;
while (lo <= hi)
{
ll mid = (lo + hi) >> 1;
if (check(mid))
lo = mid + 1, ans = mid;
else
hi = mid - 1;
}
cout << ans;
return 0;
}
