#include <bits/stdc++.h>
#define ff first
#define ss second
#define INF (1LL << 57)
using namespace std;
typedef long long int ll;
typedef pair<ll, ll> pii;
int n;
bool reach[128][128];
pii itens[128][1024];
ll g[128][128], dist[128][128], profit[128][128];
void fw(){
for(int k = 1; k <= n; ++k)
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j){
g[i][j] = min(g[i][j], g[i][k] + g[k][j]);
reach[i][j] |= (reach[i][k] && reach[k][j]);
}
}
bool fw(ll r){
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
if(reach[i][j])
dist[i][j] = r*g[i][j] - profit[i][j];
for(int k = 1; k <= n; ++k)
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j){
if(!reach[i][k] || !reach[k][j]) continue;
dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
}
for(int i = 1; i <= n; ++i)
if(dist[i][i] <= 0) return 1;
return 0;
}
void pre_calc(int k){
for(int l = 1; l <= n; ++l)
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= k; ++j)
if((itens[i][j].ss != -1) && (itens[l][j].ff != -1))
profit[l][i] = max(profit[l][i], itens[i][j].ss - itens[l][j].ff);
}
ll bin_search(ll ini, ll fim){
ll m, ans = 0;
while(fim - ini > 1){
m = (fim + ini)/2;
if(fw(m)){
ans = m;
ini = m;
}
else fim = m;
}
return ans;
}
int main(){
cin.tie(0);
ios_base::sync_with_stdio(0);
int m, k, a, b;
ll ans = 0, test = 0, c;
cin >> n >> m >> k;
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
g[i][j] = INF, dist[i][j] = INF;
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= k; ++j)
cin >> itens[i][j].ff >> itens[i][j].ss;
pre_calc(k);
for(int i = 0; i < m; ++i){
cin >> a >> b >> c;
g[a][b] = c;
reach[a][b] = 1;
}
fw();
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
test = max(test, profit[i][j]);
//cout << test << "\n";
ans = bin_search(0, test + 1);
cout << ans << "\n";
return 0;
}
