#include "bits/stdc++.h"
using namespace std;
//#define int long long
template<class T> bool umin(T& a, const T b) { if(a > b) { a = b; return 1; } return 0; }
template<class T> bool umax(T& a, const T b) { if(a < b) { a = b; return 1; } return 0; }
const int N = 105;
const int mod = 1e9+7;
const long long inf = 1e18+7;
int n, m, k, a[N][N];
int gg[N][N], b[N][1005], s[N][1005], prof[N][N];
bool check(int m){
for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) a[i][j] = -mod;
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
if(gg[i][j] == mod) continue;
umax(a[i][j], prof[i][j] - gg[i][j] * m);
}
}
for(int k=1;k<=n;k++){
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
umax(a[i][j], a[i][k] + a[k][j]);
}
}
} for(int i=1;i<=n;i++) if(a[i][i] >= 0) return 1;
return 0;
}
/*
4 5 2
10 9 5 2
6 4 20 15
9 7 10 9
-1 -1 16 11
1 2 3
2 3 3
1 4 1
4 3 1
3 1 1
*/
signed main(){
cin>>n>>m>>k;
for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) gg[i][j] = mod;
for(int i=1;i<=n;i++){
for(int j=0;j<k;j++){
cin>>b[i][j]>>s[i][j];
}
} for(int i=0;i<m;i++){
int a, b, c; cin>>a>>b>>c;
umin(gg[a][b], c);
} for(int k=1;k<=n;k++){
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
umin(gg[i][j], gg[i][k] + gg[k][j]);
}
}
} for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
for(int l=0;l<k;l++){
if(~b[i][l] && ~s[j][l]) umax(prof[i][j], - b[i][l] + s[j][l]);
}
}
}
int l = 0, r = mod;
while(l < r){
int m = (l + r + 1)>>1;
if(check(m)) l = m;
else r = m - 1;
} cout<<l<<"\n";
}
