#include <bits/stdc++.h>
#define ld long double
#define endl "\n"
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define pb(x) push_back(x)
#define mp(a,b) make_pair(a,b)
#define ms(v,x) memset(v,x,sizeof(v))
#define all(v) v.begin(),v.end()
#define ff first
#define ss second
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define per(i, a, b) for(int i = b-1; i>=a ; i--)
#define trav(a, x) for(auto& a : x)
#define allin(a , x) for(auto a : x)
#define td(v) v.begin(),v.end()
#define sz(v) (int)v.size()
//#define int long long
using namespace std;
typedef vector<int> vi;
#define y1 abacaba
#define left sefude
#define db(x) cerr << #x <<" == "<<x << endl;
#define db2(x,y) cerr<<#x <<" == "<<x<<", "<<#y<<" == "<<y<<endl;
#define db3(x,y,z) cerr << #x<<" == "<<x<<", "<<#y<<" == "<<y<<", "<<#z<<" == "<<z<<endl;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
inline ll mod(ll n, ll m ){ ll ret = n%m; if(ret < 0) ret += m; return ret; }
ll gcd(ll a, ll b){return (b == 0LL ? a : gcd(b, a%b));}
ll exp(ll a,ll b,ll m){
if(b==0LL) return 1LL;
if(b==1LL) return mod(a,m);
ll k = mod(exp(a,b/2,m),m);
if(b&1LL){
return mod(a*mod(k*k,m),m);
}
else return mod(k*k,m);
}
const int N = 105;
const int K = 1010;
ll S[N][K],B[N][K];
const ll inf = 1e9 + 2;
ll dist[N][N];
ll dp[N][N];
ll best[N][N];
int n,m,k;
bool ok(ll x){
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
dp[i][j] = -inf;
ll op1 = - dist[i][j] * x + best[i][j];
dp[i][j] = max(dp[i][j],op1);
}
}
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]);
}
}
}
if(dp[1][1] >= 0)return 1;
return 0;
}
int32_t main(){
fastio;
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] = (i==j ? 0 : inf);
best[i][j] = 0;
for(int s=1;s<=k;s++){
if(B[i][s]!=-1 and S[j][s]!=-1){
best[i][j] = max(best[i][j],S[j][s] - B[i][s]);
}
}
}
}
for(int i=0;i<m;i++){
int a,b,c;
cin >> a >> b >> c;
dist[a][b] = c;
}
dist[1][1] = inf;
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]);
}
}
}
int l = 0, r = 1e9;
int ans = 0;
while(l<=r){
int mid = (l + r)/2;
if(ok(mid)){
ans = mid;
l = mid + 1;
}else r = mid - 1;
}
cout << ans << endl;
// math -> gcd it all
// Did u check N=1? Did you switch N,M?
}
