#define DEBUG 0
#include <bits/stdc++.h>
using namespace std;
#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}
// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
public:
template<typename T>
_Debug& operator,(T val) {
cout << val << endl;
return *this;
}
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif
// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back
// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;
// ---------- END OF TEMPLATE ----------
int B[100][1000],S[100][1000];
int dist[100][100],profit[100][100];
LLI dist2[100][100];
int main() {
int i,j;
int N,M,K;
int u,v,t;
scanf("%d %d %d",&N,&M,&K);
for (i = 0; i < N; i++) {
for (j = 0; j < K; j++) scanf("%d %d",&B[i][j],&S[i][j]);
}
for (i = 0; i < N; i++) fill(dist[i],dist[i]+N,1e9);
for (i = 0; i < M; i++) {
scanf("%d %d %d",&u,&v,&t);
u--,v--;
dist[u][v] = min(dist[u][v],t);
}
int k;
for (k = 0; k < N; k++) {
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) dist[i][j] = min(dist[i][j],dist[i][k]+dist[k][j]);
}
}
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
int m = 0;
for (k = 0; k < K; k++) {
if ((B[i][k] != -1) && (S[j][k] != -1)) m = max(m,S[j][k]-B[i][k]);
}
profit[i][j] = m;
}
}
int l = 0,r = 1e9;
while (l < r) {
int m = (l+r+1) / 2;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) dist2[i][j] = profit[i][j]-(LLI) m*dist[i][j];
}
for (k = 0; k < N; k++) {
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) dist2[i][j] = max(dist2[i][j],dist2[i][k]+dist2[k][j]);
}
}
for (i = 0; i < N; i++) {
if (dist2[i][i] >= 0) break;
}
if (i < N) l = m;
else r = m-1;
}
printf("%d\n",l);
return 0;
}
