#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
struct pair_hash{
size_t operator()(const pair<int,int>&x)const{
return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32));
}
};
const int MAXN = 107;
const int MAXK = 1e3 + 7;
const ll INF = 1e16;
ll dist[MAXN][MAXN];
ll C[MAXN][MAXN];
ll B[MAXN][MAXK];
ll S[MAXN][MAXK];
ll g[MAXN][MAXN];
int n, m, K;
int main(){
ios_base::sync_with_stdio(0);
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 >> 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 a, b;
ll c;
cin >> a >> b >> c;
dist[a][b] = c;
}
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], (ll)dist[i][k] + dist[k][j]);
}
}
}
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
C[i][j] = 0LL;
for(int k = 1; k <= n; k++){
if((B[i][k] != -1LL) && (S[j][k] != -1LL)){
C[i][j] = max(C[i][j], (ll)S[j][k] - B[i][k]);
}
}
}
}
int l = 1;
int p = (int)1e9;
int mid;
while(l <= p){
mid = (l + p) / 2;
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
if(dist[i][j] == INF){
g[i][j] = INF;
}else{
g[i][j] = (ll)mid * dist[i][j] - C[i][j];
}
}
}
for(int k = 1; k <= n; k++){
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
g[i][j] = min((ll)g[i][j], (ll)g[i][k] + g[k][j]);
}
}
}
bool f = false;
for(int i = 1; i <= n; i++){
if(g[i][i] <= 0LL){
f = true;
}
}
if(f){
l = mid + 1;
}else{
p = mid - 1;
}
}
cout << p << '\n';
return 0;
}
