#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
#define f first
#define s second
const int N = 100 + 100;
const int K = 1000 + 100;
const ll mod = 998244353;
const ll inf = 1e9 + 100;
int n, m, k;
ll dis[N][N], Dis[N][N], prf[N][N], s[N][K], b[N][K];
inline bool check(ll mid)
{
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
if(dis[i][j] == inf)
Dis[i][j] = -inf;
else
Dis[i][j] = prf[i][j] - dis[i][j] * mid;
}
Dis[i][i] = -inf;
}
/*
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
cout << i+1 << ' ' << j+1 << ' ' << Dis[i][j] << endl;
}
}
*/
for(int t = 0; t < n; t++)
{
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
Dis[i][j] = max(Dis[i][j], Dis[i][t] + Dis[t][j]);
}
}
}
for(int i = 0; i < n; i++)
{
if(Dis[i][i] >= 0)
return 1;
}
return 0;
}
inline void floyd()
{
for(int t = 0; t < n; t++)
{
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
dis[i][j] = min(dis[i][j], dis[i][t] + dis[t][j]);
}
}
}
}
inline ll max_profit(int u, int v)
{
ll ans = 0;
for(int i = 0; i < k; i++)
{
if(s[v][i] != -1 && b[u][i] != -1)
ans = max(ans, s[v][i] - b[u][i]);
}
return ans;
}
int main()
{
ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
cin >> n >> m >> k;
for(int i = 0; i < n; i++)
{
for(int j = 0; j < k; j++)
{
cin >> b[i][j] >> s[i][j];
}
}
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
dis[i][j] = inf;
prf[i][j] = max_profit(i, j);
}
dis[i][i] = 0;
}
for(int i = 0; i < m; i++)
{
int x, y, w;
cin >> x >> y >> w;
x--; y--;
dis[x][y] = w;
}
floyd();
/*
cout << "//////////////////////////////////" << endl;
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
cout << i+1 << ' ' << j+1 << ' ' << dis[i][j] << ' ' << prf[i][j] << endl;
}
}
cout << "//////////////////////////////////" << endl;
*/
ll l = 0, r = inf;
while(l + 1 < r)
{
ll mid = (l + r) / 2;
if(check(mid))
{
l = mid;
}
else
{
r = mid;
}
}
cout << l << endl;
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
*/
