#include<bits/stdc++.h>
#include<stdint.h>
using namespace std;
#define IOS {cin.tie(0);ios_base::sync_with_stdio(false);}
#define int int64_t
#define N 105
#define K 1005
const int INF = 1e17;
const double eps = 1e-2;
int bb[N][K],ss[N][K];
int w[N][N],dis[N][N];
double dp[N][N];
bitset<N> vis;
vector<pair<int,int> > v[N];
int32_t main()
{
IOS;
int n,m,k,a,b,t;
cin >> n >> m >> k;
for(int i=1;i<=n;i++) for(int j=1;j<=k;j++) cin >> bb[i][j] >> ss[i][j];
for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) dis[i][j] = INF;
for(int i=1;i<=n;i++) dis[i][i] = 0;
for(int i=0;i<m;i++){
cin >> a >> b >> t;
dis[a][b] = t;
}
for(int x=1;x<=n;x++) for(int i=1;i<=n;i++) for(int j=1;j<=n;j++)
dis[i][j] = min(dis[i][j],dis[i][x] + dis[x][j]);
for(int i=1;i<=n;i++) for(int j=1;j<=n;j++){
if(j != i && dis[i][j] != INF) {
for(int x=1;x<=k;x++) if(ss[j][x] >= 0 && bb[i][x] >= 0) w[i][j] = max(w[i][j],ss[j][x] - bb[i][x]);
}
else w[i][j] = 0;
}
// cout << "dis :\n";
// for(int i=1;i<=n;i++,cout << '\n') for(int j=1;j<=n;j++)cout << dis[i][j] << ' ';
// cout << "w :\n";
// for(int i=1;i<=n;i++,cout << '\n') for(int j=1;j<=n;j++)cout << w[i][j] << ' ';
double l=0,r = 1e14;
for(int cnt=0;cnt<100;cnt++){
double mm = (l+r)*0.5;
for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) {
dp[i][j] = mm*dis[i][j] - w[i][j];
}
// cout << "mm = " << mm << '\n';
// cout << "dp :\n";
// for(int i=1;i<=n;i++,cout << '\n') for(int j=1;j<=n;j++)cout << fixed << setprecision(1) << dp[i][j] << ' ';
for(int x=1;x<=n;x++) for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) {
dp[i][j] = min(dp[i][j],dp[i][x] + dp[x][j]);
}
bool gg = false;
for(int i=1;i<=n;i++) if(dp[i][i] < 0) gg = true;
if(gg) l = mm;
else r = mm;
}
cout << (int)(floor(l+eps)+0.5) << '\n';
return 0;
}
