//Be Name Khoda
#include<bits/stdc++.h>
#pragma GCC target ("avx2,tune=native")
using namespace std;
#define ll long long
#define ld long double
#define all(x) x.begin(), x.end()
#define pii pair<int, int>
#define piii pair<pii, int>
#define piiii pair<pii, pii>
#define piiiii pair<pii, piii>
#define pll pair<ll, ll>
#define plll pair<pll, ll>
const ll mxn = 116, MXN = 1016;
ll n, m, k, q;
ll dis[mxn][mxn], f[mxn][mxn], b[mxn][MXN], s[mxn][MXN];
vector<pll> adj[mxn];
bool check(ll x) {
ll d[mxn][mxn];
for(int i = 0; i <= n; i++) {
for(int j = 0; j <= n; j++) {
d[i][j] = -1LL * MXN * MXN * MXN;
}
}
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
d[i][j] = f[i][j] + -1LL * x * dis[i][j];
}
}
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
for(int w = 1; w <= n; w++) {
d[j][w] = max(d[j][w], d[j][i] + d[i][w]);
}
}
}
for(int i = 1; i <= n; i++) {
if(d[i][i] > 0) {
return 1;
}
if(d[i][i] < 0) continue;
for(int j = 1; j <= n; j++) {
if(d[i][j] + d[j][i] == d[i][i] && i != j) {
return 1;
}
}
}
return 0;
}
ll bs(ll l, ll r) {
if(r - l == 1) return l;
ll mid = (l + r) >> 1;
if(check(mid)) {
return bs(mid, r);
}
return bs(l, mid);
}
void input() {
for(int i = 0; i < mxn; i++) {
for(int j = 0; j < mxn; j++) {
dis[i][j] = 1LL * MXN * MXN * MXN;
}
dis[i][i] = 0;
}
cin >> n >> m >> k;
for(int i = 1; i <= n; i++) {
for(int j = 0; j < k; j++) {
cin >> b[i][j] >> s[i][j];
}
}
for(int i = 0; i < m; i++) {
ll v, u;
cin >> v >> u >> q;
adj[v].push_back({u, q});
dis[v][u] = min(dis[v][u], q);
}
}
void solve() {
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
for(int w = 1; w <= n; w++) {
dis[j][w] = min(dis[j][w], dis[j][i] + dis[i][w]);
}
for(int w = 0; w < k; w++) {
if(b[i][w] != -1 && s[j][w] != -1) {
f[i][j] = max(f[i][j], s[j][w] - b[i][w]);
}
}
}
}
cout << bs(0LL, 1LL* MXN * MXN * MXN) << endl;
}
int main() {
ios::sync_with_stdio(false); cin.tie(NULL);
input(), solve();
return 0;
}
