#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
const ll inf = 1121272678990188431;
const int maxn = 1e2+10, maxk = 1e3+10;
ll b[maxn][maxk], s[maxn][maxk], dis[maxn][maxn], new_w[maxn][maxn], max_ben[maxn][maxn];
int n, m, k;
void FloydWarshall(ll d[maxn][maxn])
{
for(int w = 0; w < n; w++)
for(int v = 0; v < n; v++)
for(int u = 0; u < n; u++)
d[v][u] = min(d[v][u], d[v][w] + d[w][u]);
return;
}
void CalcBen()
{
for(int v = 0; v < n; v++)
for(int u = 0; u < n; u++)
for(int l = 0; l < k; l++)
if(b[v][l] != -1 && s[u][l] != -1)
max_ben[v][u] = max(max_ben[v][u], s[u][l] - b[v][l]);
return;
}
bool Valid(ll x)
{
for(int v = 0; v < n; v++)
{
for(int u = 0; u < n; u++)
{
if(dis[v][u] == inf)
new_w[v][u] = inf;
else
new_w[v][u] = x * dis[v][u] - max_ben[v][u];
}
}
FloydWarshall(new_w);
for(int v = 0; v < n; v++)
if(new_w[v][v] <= 0)
return true;
return false;
}
ll Bs(ll l, ll r)
{
if((r - l) <= 1)
return l;
ll mid = (l + r) / 2;
if(Valid(mid))
return Bs(mid, r);
else
return Bs(l, mid);
}
int main()
{
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++)
fill(dis[i], dis[i] + n, inf);
for(int i = 0; i < m; i++)
{
int v, u;
ll w;
cin >> v >> u >> w;
v--, u--;
dis[v][u] = w;
}
FloydWarshall(dis);
CalcBen();
ll ans = Bs(0, 1e9+10);
cout << ans << '\n';
}
