#include <bits/stdc++.h>
#include <bits/extc++.h>
#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define ef(a) emplace_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define tomax(a, b) ((a) = max((a), (b)))
#define tomin(a, b) ((a) = min((a), (b)))
#define topos(a) ((a) = (((a) % MOD + MOD) % MOD))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
if(pvaspace) b << " "; pvaspace=true;\
b << pva;\
}\
b << "\n";}
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;
const ll MOD = 1000000007;
const ll MAX = 2147483647;
template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
return o << '(' << p.F << ',' << p.S << ')';
}
ll ifloor(ll a, ll b){
if(b < 0) a *= -1, b *= -1;
if(a < 0) return (a - b + 1) / b;
else return a / b;
}
ll iceil(ll a, ll b){
if(b < 0) a *= -1, b *= -1;
if(a > 0) return (a + b - 1) / b;
else return a / b;
}
int n, m, K;
vector<vector<ll>> gv, gt;
bool check(ll x){
vector<vector<ll>> dis(n + 1, vector<ll>(n + 1, 1LL << 60));
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
if(gt[i][j] != -1) dis[i][j] = -gv[i][j] + gt[i][j] * x;
}
}
for(int k = 1; k <= n; k++){
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
dis[i][j] = min(dis[i][j], dis[i][k] + dis[k][j]);
}
}
}
// cerr << "test " << x << "\n";
// for(int i =1 ; i <= n; i++) printv(dis[i], cerr);
ll ans = 1LL << 60;
for(int i = 1; i <= n; i++) ans = min(ans, dis[i][i]);
return ans <= 0;
}
int main(){
StarBurstStream
cin >> n >> m >> K;
vector<vector<ll>> buy(n + 1, vector<ll>(K + 1));
vector<vector<ll>> sell(n + 1, vector<ll>(K + 1));
gv.resize(n + 1, vector<ll>(n + 1));
gt.resize(n + 1, vector<ll>(n + 1, MAX));
for(int i = 1; i <= n; i++){
for(int j = 1; j <= K; j++){
cin >> buy[i][j] >> sell[i][j];
}
}
for(int i = 0; i < m; i++){
int u, v, w;
cin >> u >> v >> w;
gt[u][v] = w;
}
for(int k = 1; k <= n; k++){
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
gt[i][j] = min(gt[i][j], gt[i][k] + gt[k][j]);
}
}
}
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
if(gt[i][j] == MAX) continue;
for(int k = 1; k <= K; k++){
if(buy[i][k] == -1 || sell[j][k] == -1) continue;
gv[i][j] = max(gv[i][j], sell[j][k] - buy[i][k]);
}
}
}
// for(int i = 1; i <= n; i++) printv(gv[i], cerr);
ll l = 0, r = 1000000000;
while(l < r){
ll mid = (l + r + 1) / 2;
if(check(mid)) l = mid;
else r = mid - 1;
}
cout << l << "\n";
return 0;
}
