#include <bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(0);cin.tie(0);
typedef long long ll;
#define f first
#define s second
#define MOD 998244353
#define LOGN 21
#define MAXN 105
#define int long long
int temp[MAXN][MAXN], dist[MAXN][MAXN], sell[MAXN][MAXN];
int N, market[MAXN][1005][2];
const ll INF = LLONG_MAX / 2;
bool check(int K) {
for (int i = 1; i <= N; i++) {
for (int j = 1; j <= N; j++)
temp[i][j] = - sell[i][j] + K * min(dist[i][j], INF / K);
}
for (int k = 1; k <= N; k++) {
for (int i = 1; i <= N; i++) {
for (int j = 1; j <= N; j++)
temp[i][j] = min(temp[i][j], temp[i][k] + temp[k][j]);
}
}
for (int i = 1; i <= N; i++) {
if (temp[i][i] <= 0)
return true;
}
return false;
}
signed main() {
fast
int M, K;
cin >> N >> M >> K;
for (int i = 0; i < MAXN; i++) {
for (int j = 0; j < MAXN; j++)
dist[i][j] = INF;
}
for (int i = 1; i <= N; i++) {
for (int j = 1; j <= K; j++)
cin >> market[i][j][0] >> market[i][j][1];
}
for (int i = 0; i < M; i++) {
int from, to, T;
cin >> from >> to >> T;
dist[from][to] = min(dist[from][to], T);
}
for (int k = 1; k <= N; k++) {
for (int i = 1; i <= N; i++) {
for (int j = 1; j <= N; j++)
dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
}
}
for (int i = 1; i <= N; i++) {
for (int j = 1; j <= N; j++) {
for (int k = 1; k <= K; k++) {
if (market[j][k][1] != -1 && market[i][k][0] != -1)
sell[i][j] = max(sell[i][j], market[j][k][1] - market[i][k][0]);
}
}
}
int L = 1;
int R = 1e9;
int ans = -1;
while (R >= L) {
int mid = L + (R-L) / 2;
if (check(mid)) {
ans = mid;
L = mid + 1;
} else
R = mid - 1;
}
cout << ans << "\n";
}
