// Starcraft 2 enjoyer //
#include <bits/stdc++.h>
// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
#define LSOne(X) ((X) & -(X))
#define int long long
const int N = 1e2 + 5;
const int M = 1e6 + 5;
const int K = 301;
const int LG = 60;
const int INF = 1e18 + 5;
const int B = 1000;
const int MOD = 1e9 + 7;
int n, m, k, b[N][K], s[N][K], dis[N][N], mx[N][N], dp[N][N], gud[N][N], ans;
inline void solve()
{
cin >> n >> m >> k;
for (int x = 1; x <= n; x++)
{
for (int y = 0; y < k; y++)
{
cin >> b[x][y] >> s[x][y];
}
}
for (int x = 1; x <= n; x++)
{
for (int y = 1; y <= n; y++)
{
dis[x][y] = INF;
mx[x][y] = 0;
}
}
for (int x = 0; x < m; x++)
{
int a, b, w;
cin >> a >> b >> w;
dis[a][b] = min(dis[a][b], w);
}
for (int x = 1; x <= n; x++)
{
for (int y = 1; y <= n; y++)
{
for (int z = 1; z <= n; z++)
{
dis[y][z] = min(dis[y][z], dis[y][x] + dis[x][z]);
}
}
}
for (int x = 1; x <= n; x++)
{
for (int y = 1; y <= n; y++)
{
if(x == y) continue;
if(dis[x][y] == INF) continue;
for (int z = 0; z < k; z++)
{
if (b[x][z] == -1 || s[y][z] == -1)
continue;
mx[x][y] = max(mx[x][y], s[y][z] - b[x][z]);
}
}
}
int l = 0, r = 1e9;
while (l <= r)
{
int m = (l + r) / 2;
for (int x = 1; x <= n; x++)
{
for (int y = 1; y <= n; y++)
{
dp[x][y] = INF;
gud[x][y] = 0;
}
}
for (int x = 1; x <= n; x++)
{
dp[x][x] = 0;
}
for (int y = 1; y <= n; y++)
{
for (int z = 1; z <= n; z++)
{
if (dis[y][z] == INF)
continue;
dp[y][z] = -(mx[y][z] - m * dis[y][z]);
// cout << dp[y][z] << " " << y << " " << z << "\n";
}
}
for (int x = 1; x <= n; x++)
{
for (int y = 1; y <= n; y++)
{
for (int z = 1; z <= n; z++)
{
if (x == y && y == z)
continue;
dp[y][z] = min(dp[y][z], dp[y][x] + dp[x][z]);
if (dp[y][z] == dp[y][x] + dp[x][z])
gud[y][z] = 1;
}
}
}
bool b = 0;
for (int x = 1; x <= n; x++)
{
if (gud[x][x] && dp[x][x] <= 0)
{
// cout << dp[x][x] << " " << m << "\n";
b = 1;
}
}
if (b)
{
ans = m;
l = m + 1;
}
else
{
r = m - 1;
}
}
cout << ans;
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
for (int x = 1; x <= t; x++)
{
solve();
}
return 0;
}
