#include <bits/stdc++.h>
#define N 105
#define M 1005
#define inf 1000000000000000000
using namespace std;
typedef long long ll;
int n, m, k;
ll opt[N][N], B[N][M], S[N][M], dist[N][N], dp[N][N];
inline bool check(ll x)
{
for(int i = 1; i <= n; i++)
{
for(int j = 1; j <= n; j++)
if(dist[i][j] == inf) dp[i][j] = inf;
else dp[i][j] = x*dist[i][j] - opt[i][j];
}
for(int k = 1; k <= n; k++)
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
dp[i][j] = min(dp[i][j], dp[i][k] + dp[k][j]);
for(int i = 1; i <= n; i++) if(dp[i][i] <= 0) return true;
return false;
}
int main()
{
ios::sync_with_stdio(false); 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 = 1; j <= n; j++)
dist[i][j] = inf;
for(int i = 1, a, b, c; i <= m; i++)
{
cin>>a>>b>>c;
dist[a][b] = c;
}
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
for(int q = 1; q <= k; q++)
if(B[i][q] >= 0 and S[j][q] >= 0) opt[i][j] = max(opt[i][j], -B[i][q] + S[j][q]);
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]);
ll ini = 0, fim = 1e9 + 500, mid, best = 0;
while(fim >= ini)
{
mid = (ini + fim)/2;
if(check(mid)) best = mid, ini = mid + 1;
else fim = mid - 1;
}
cout<<best<<"\n";
}
