#include <bits/stdc++.h>
using namespace std;
#define int long long
#define inf 0x3F3F3F3F
const int MXN = 2e2 + 5;
const int MXM = 1e3 + 5;
int n, m, k;
int d[MXN][MXN], nd[MXN][MXN], w[MXN][MXN];
int B[MXN][MXM], S[MXN][MXM];
// 0 >= x * t - p
int ok(int val)
{
for (int i = 1; i <= n; i++)
{
for (int j = 1; j <= n; j++)
{
nd[i][j] = d[i][j] * val - w[i][j];
}
}
for (int k = 1; k <= n; k++)
{
for (int i = 1; i <= n; i++)
{
for (int j = 1; j <= n; j++)
{
nd[i][j] = min(nd[i][j], nd[i][k] + nd[k][j]);
}
}
}
for (int i = 1; i <= n; i++)
{
if (nd[i][i] <= 0) return 1;
}
return 0;
}
signed 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 <= n; j++)
{
d[i][j] = inf;
}
}
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 <= m; i++)
{
int u, v, t;
cin >> u >> v >> t;
d[u][v] = min(d[u][v], t);
}
for (int i = 1; i <= n; i++)
{
for (int j = 1; j <= n; j++)
{
for (int l = 1; l <= k; l++)
{
if (B[i][l] != -1 && S[j][l] != -1) w[i][j] = max(w[i][j], S[j][l] - B[i][l]);
}
}
}
for (int k = 1; k <= n; k++)
{
for (int i = 1; i <= n; i++)
{
for (int j = 1; j <= n; j++)
{
d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
}
}
}
int l = 0, r = inf;
while (l < r)
{
int mid = (l + r + 1) >> 1;
if (ok(mid)) l = mid;
else r = mid - 1;
}
cout << l << '\n';
}
