#include <bits/stdc++.h>
using namespace std;
const int N = 101;
const int K = 1001;
int n,m,k;
int b[N][K],s[N][K];
int diso[N][N],sell[N][N];
long long dist[N][N];
bool solve(long long x)
{
for(int i = 1;i <= n;i++) for(int j = 1;j <= n;j++) dist[i][j] = (long long)diso[i][j]*x-(long long)sell[i][j];
for(int i = 1;i <= n;i++) dist[i][i] = INT_MAX;
for(int k = 1;k <= n;k++) for(int i = 1;i <= n;i++) for(int j = 1;j <= n;j++)
dist[i][j] = min(dist[i][j],dist[i][k]+dist[k][j]);
for(int i = 1;i <= n;i++) if(dist[i][i]<=0) return true;
return false;
}
int main()
{
ios_base::sync_with_stdio(0); cin.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];
for(int i = 1;i <= n;i++) for(int j = i+1;j <= n;j++) diso[i][j] = diso[j][i] = INT_MAX;
for(int i = 0;i < m;i++)
{
int a,b,d;
cin >> a >> b >> d;
diso[a][b] = min(diso[a][b],d);
}
for(int k = 1;k <= n;k++) for(int i = 1;i <= n;i++) for(int j = 1;j <= n;j++)
if(diso[i][k]!=INT_MAX and diso[k][j]!=INT_MAX) diso[i][j] = min(diso[i][j],diso[i][k]+diso[k][j]);
for(int i = 1;i <= n;i++) for(int j = 1;j <= n;j++) for(int l = 1;l <= k;l++)
if(s[j][l]>0 and b[i][l]>0) sell[i][j] = max(sell[i][j],s[j][l]-b[i][l]);
long long l = 0,r = 1e9;
while(l<r)
{
long long m = (l+r+1LL)/2LL;
if(solve(m)) l = m;
else r = m-1;
}
cout << l;
}
