// #pragma GCC target( "sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
// #pragma GCC optimize("Ofast,unroll-loops,fast-math,O3")
#include<bits/stdc++.h>
#define f first
#define s second
#define pb push_back
#define sz(x) (int)x.size()
#define bit(a, i) ((a>>i)&1)
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int K = 210;
const ll inf = 1e18;
const int mod = 1e9 + 7;
const int maxn = 1e3 + 100;
int n, m, k;
ll d[maxn][maxn];
ll b[maxn][maxn];
ll c[maxn][maxn];
ll s[maxn][maxn];
ll d1[maxn][maxn];
ll d2[maxn][maxn];
int add(ll a, ll b){
return (a+b)%mod;
}
bool ok(int x){
for(int i=1; i<=n; i++){
for(int j=1; j<=n; j++){
d1[i][j] = x*1ll*d[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++){
d1[i][j] = min(d1[i][j], d1[i][k]+d1[k][j]);
}
}
}
for(int i=1; i<=n; i++){
for(int j=1; j<=n; j++){
d2[i][j] = d1[i][j];
}
}
for(int k=1; k<=n; k++){
for(int i=1; i<=n; i++){
for(int j=1; j<=n; j++){
d1[i][j] = min(d1[i][j], d1[i][k]+d1[k][j]);
}
}
}
for(int i=1; i<=n; i++){
for(int j=1; j<=n; j++){
if(d1[i][j] != d2[i][j]) return 1;
}
}
return 0;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
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];
}
fill(d[i], d[i]+n+1, inf);
d[i][i] = 0;
}
for(int i=1; i<=n; i++){
for(int j=1; j<=n; j++){
for(int l=1; l<=k; l++){
if(b[i][l] == -1 || s[j][l] == -1) continue;
c[i][j] = max(c[i][j], s[j][l]-b[i][l]);
}
}
}
for(int i=1; i<=m; i++){
int u, v, w;
cin >> u >> v >> w;
d[u][v] = min(d[u][v], w*1ll);
d[v][u] = min(d[v][u], w*1ll);
}
for(int k=1; k<=n; k++){
for(int i=1; i<=n; i++){
for(int j=1; j<=n; j++){
if(max(d[i][k], d[k][j]) < inf){
d[i][j] = min(d[i][j], d[i][k]+d[k][j]);
}
}
}
}
int ans = 0;
for(int l=1, r=1e9; l<=r;){
int mid = (l+r)>>1;
if(!ok(mid)) r = mid - 1;
else l = mid + 1, ans = mid;
}
cout << ans;
}
