#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}());
const ll mod=1000000007;
const ll mod2=998244353;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head
const int N=1010;
int n,m,k,b[N][N],s[N][N],a[N][N];
ll d[N][N];
db dis[N][N];
bool check(ll x) {
rep(i,1,n+1) rep(j,1,n+1) dis[i][j]=x*min((ll)d[i][j],(ll)1e18/x)-a[i][j];
rep(p,1,n+1) rep(i,1,n+1) rep(j,1,n+1) dis[i][j]=min(dis[i][j],dis[i][p]+dis[p][j]);
rep(i,1,n+1) if (dis[i][i]<=0) return 1;
return 0;
}
int main() {
scanf("%d%d%d",&n,&m,&k);
rep(i,1,n+1) rep(j,1,k+1) scanf("%d%d",&b[i][j],&s[i][j]);
rep(i,1,n+1) rep(j,1,n+1) d[i][j]=(1LL<<59);
rep(i,1,m+1) {
int u,v,w;
scanf("%d%d%d",&u,&v,&w);
d[u][v]=min(d[u][v],(ll)w);
}
rep(p,1,n+1) rep(i,1,n+1) rep(j,1,n+1) d[i][j]=min(d[i][j],d[i][p]+d[p][j]);
rep(i,1,n+1) rep(j,1,n+1) rep(p,1,k+1) {
if (s[i][p]!=-1&&b[j][p]!=-1) a[i][j]=max(a[i][j],s[i][p]-b[j][p]);
}
ll l=1,r=1e9,ans=0;
while (l<=r) {
ll md=l+r>>1;
if (check(md)) ans=md,l=md+1;
else r=md-1;
}
printf("%lld",ans);
}
