#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pb(e) push_back(e)
#define sv(a) sort(a.begin(),a.end())
#define sa(a,n) sort(a,a+n)
#define mp(a,b) make_pair(a,b)
#define vf first
#define vs second
#define ar array
#define all(x) x.begin(),x.end()
const int inf = 0x3f3f3f3f;
const int mod = 1000000007;
const double PI=3.14159265358979323846264338327950288419716939937510582097494459230;
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
bool remender(ll a , ll b){return a%b;}
//freopen("problemname.in", "r", stdin);
//freopen("problemname.out", "w", stdout);
void solve(){
int n , m , k;
cin >> n >> m >> k;
int b[n][k],s[n][k];
for(int i = 0; i < n; i++){
for(int j = 0; j < k; j++)cin>>b[i][j] >> s[i][j];
}
ll dis[n][n];
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++)dis[i][j] = 1e18;
}
for(int i = 0; i < m; i++){
int a , bb , c;
cin >> a >> bb >> c;
a--;
bb--;
dis[a][bb] = c;
}
for(int a = 0; a < n; a++){
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
dis[i][j] = min(dis[i][j] , dis[i][a] + dis[a][j]);
}
}
}
ll profit[n][n];
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
profit[i][j] = 0;
for(int a = 0; a < k; a++){
if(b[i][a] != -1 && s[j][a] != -1)
profit[i][j] = max(profit[i][j] , (ll)-b[i][a] +s[j][a]);
}
}
}
ll l = 1 , r = 1e11 , ans = 0;
ll new_dis[n][n];
while(l <= r){
ll mid = (l + r)/2;
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
ll need = (1e16/mid);
need++;
new_dis[i][j] = profit[i][j] - min(need , dis[i][j])*mid;
}
}
for(int a = 0; a < n; a++){
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
new_dis[i][j] = max(new_dis[i][j] , new_dis[i][a] + new_dis[a][j]);
}
}
}
ll mx = -1e18;
for(int i = 0; i < n; i++){
mx = max(mx , new_dis[i][i]);
}
if(mx >= 0){
ans = mid;
l = mid + 1;
}
else r = mid - 1;
}
cout << ans << '\n';
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
//int t;cin >> t;while(t--)
solve();
return 0;
}
