#include <bits/stdc++.h>
using namespace std;
#define POPCOUNT(n) (__builtin_popcountll((n)))
#define CLZ(n) (__builtin_clzll((n)))
#define CTZ(n) (__builtin_ctzll((n)))
#define LOG(n) (63 - __builtin_clzll((n)))
#define BIT(n, i) (((n) >> (i)) & 1ll)
#define MASK(i) (1ll << (i))
#define FLIP(n, i) ((n) ^ (1ll << (i)))
#define ON(n, i) ((n) | MASK(i))
#define OFF(n, i) ((n) & ~MASK(i))
#define Int __int128
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long long, int> pli;
typedef pair<int, long long> pil;
typedef vector<pair<int, int>> vii;
typedef vector<pair<long long, long long>> vll;
typedef vector<pair<long long, int>> vli;
typedef vector<pair<int, long long>> vil;
template <class T1, class T2> bool maximize(T1 &x, T2 y) {
if (x < y) {
x = y;
return true;
}
return false;
}
template <class T1, class T2> bool minimize(T1 &x, T2 y) {
if (x > y) {
x = y;
return true;
}
return false;
}
template <class T> void remove_duplicate(vector<T> &ve) {
sort (ve.begin(), ve.end());
ve.resize(unique(ve.begin(), ve.end()) - ve.begin());
}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
long long random(long long l, long long r) {
return uniform_int_distribution<long long>(l, r)(rng);
}
template <class T> T random(T r) {
return rng() % r;
}
const int N = 100 + 5, K = 1000 + 5;
const int MOD = 1e9 + 7;
const int inf = 1e9;
const long long INF = 1e18;
int n, m, k;
int buy[N][K], sell[N][K];
ll dist[N][N], dist2[N][N], profit[N][N];
bool check(ll t) {
for (int i = 1; i <= n; ++i) for (int j = 1; j <= n; ++j) {
dist2[i][j] = t * min(dist[i][j], INF / t) - profit[i][j];
}
for (int k = 1; k <= n; ++k) for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j)
minimize(dist2[i][j], dist2[i][k] + dist2[k][j]);
}
for (int i = 1; i <= n; ++i)
if (dist2[i][i] <= 0) return true;
return false;
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n >> m >> k;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= k; ++j) {
cin >> buy[i][j] >> sell[i][j];
}
}
memset(dist, 0x0f, sizeof dist);
// for (int i = 1; i <= n; ++i) dist[i][i] = 0;
for (int i = 1; i <= m; ++i) {
int u, v, w; cin >> u >> v >> w;
minimize(dist[u][v], w);
}
for (int k = 1; k <= n; ++k) for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j)
minimize(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 x = 1; x <= k; ++x)
if (sell[j][x] != -1 && buy[i][x] != -1) maximize(profit[i][j], sell[j][x] - buy[i][x]);
}
ll low = 1, high = 1ll * inf * n, ans = -1;
while (low <= high) {
ll mid = (low + high) >> 1;
if (check(mid)) low = (ans = mid) + 1;
else high = mid - 1;
}
cout << ans;
return 0;
}
