#pragma GCC target("avx2")
#pragma GCC optimize("O3")
# include <x86intrin.h>
# include <bits/stdc++.h>
# include <ext/pb_ds/assoc_container.hpp>
# include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
template<typename T> using ordered_set = tree <T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define _USE_MATH_DEFINES_
#define ll long long
#define ld long double
#define Accepted 0
#define pb push_back
#define mp make_pair
#define sz(x) (int)(x.size())
#define every(x) x.begin(),x.end()
#define F first
#define S second
#define lb lower_bound
#define ub upper_bound
#define For(i,x,y) for (ll i = x; i <= y; i ++)
#define FOr(i,x,y) for (ll i = x; i >= y; i --)
#define SpeedForce ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
// ROAD to... Red
inline void Input_Output () {
//freopen(".in", "r", stdin);
//freopen(".out", "w", stdout);
}
const double eps = 0.000001;
const ld pi = acos(-1);
const int maxn = 1e7 + 9;
const int mod = 1e9 + 7;
const ll MOD = 1e18 + 9;
const ll INF = 1e18 + 123;
const int inf = 1e9 + 11;
const int mxn = 1e6 + 9;
const int N = 6e5 + 123;
const int M = 22;
const int pri = 997;
const int Magic = 2101;
#define int long long
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};
int n, m, k;
int b[152][1052];
int s[152][1052];
int dist[152][152];
int cost[152][152];
int nw[152];
vector < int > g[145];
int dp[152][152];
main () {
SpeedForce;
cin >> n >> m >> k;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= k; ++j)
cin >> b[i][j] >> s[i][j];
}
for (int i = 1; i <= n; i ++)
for (int j = 1; j <= n; j ++)
dist[i][j] = inf;
for (int i = 1; i <= m; i ++) {
int x, y, z;
cin >> x >> y >> z;
dist[x][y] = z;
}
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 it = 1; it <= k; ++it) {
if (s[j][it] != -1 && b[i][it] != -1)
cost[i][j] = max(cost[i][j], s[j][it] - b[i][it]);
}
}
}
int l = 0, r = 1e9 + 1;
while (l + 1 < r) {
int md = (l + r) >> 1;
for (int i = 1; i <= n; i ++) {
for (int j = 1; j <= n; j ++) {
dp[i][j] = cost[i][j] - dist[i][j] * (ll)md;
}
}
for (int k = 1; k <= n; k++)
for (int i = 1; i <= n; i ++) {
for (int j = 1; j <= n; j ++) {
dp[i][j] = max(dp[i][j], dp[i][k] + dp[k][j]);
}
}
bool good = 0;
for (int i = 1; i <= n; i ++)
if(dp[i][i] >= 0) good = 1;
if(good) l = md;
else r = md;
}
cout << l << '\n';
return Accepted;
}
// B...a
