#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;
const int MAXN = 100;
const int MAXK = 1000;
const ll inf = 1e18;
const ld ERROR = 1e-9;
int n, m, k;
vector<pii> edges[MAXN];
ll dist[MAXN][MAXN];
ld bfdist[MAXN];
int val[MAXN][MAXN];
int buy[MAXN][MAXK];
int sell[MAXN][MAXK];
bool neg_cycle(ld ben) {
fill(bfdist, bfdist+n, inf);
bfdist[0] = 0;
bool f = 1;
for (int i = 0; i < n && f; i++) {
f = 0;
for (int a = 0; a < n; a++) {
for (int b = 0; b < n; b++) {
ld w = ben*dist[a][b]-val[a][b];
if (bfdist[b] > bfdist[a]+w+ERROR) {
bfdist[b] = bfdist[a]+w;
f = 1;
}
}
}
}
return f;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
cin >> n >> m >> k;
for (int i = 0; i < n; i++) {
for (int j = 0; j < k; j++) {
cin >> buy[i][j];
cin >> sell[i][j];
}
fill(dist[i], dist[i]+n, inf);
dist[i][i] = 0;
}
for (int i = 0; i < m; i++) {
int x, y, w;
cin >> x >> y >> w;
x--; y--;
edges[x].push_back(pii(y, w));
dist[x][y] = w;
}
for (int i = 0; i < n; i++) {
for (int a = 0; a < n; a++) {
for (int b = 0; b < n; b++) dist[a][b] = min(dist[a][b], dist[a][i]+dist[i][b]);
}
}
for (int a = 0; a < n; a++) {
for (int b = 0; b < n; b++) {
for (int i = 0; i < k; i++) {
if (buy[a][i] != -1 && sell[b][i] != -1)
val[a][b] = max(val[a][b], sell[b][i]-buy[a][i]);
}
}
}
int mn = 0;
int mx = 1e9;
while (mx > mn+1) {
int cur = (mn+mx)/2;
if (neg_cycle(cur-ERROR)) mn = cur;
else mx = cur;
}
cout << mn << "\n";
}
