#include <iostream>
using namespace std;
#define ll long long
int n, m, k;
const ll inf = 1e18 + 69;
ll dist[105][105], profit[105][105];
ll res[105][105];
ll buy[105][1005], sell[105][1005];
bool check(ll penalty){
for(int u = 1; u <= n; u ++) for(int v = 1; v <= n; v ++){
if(dist[u][v] == inf) res[u][v] = -inf;
else res[u][v] = max((ll)profit[u][v] - dist[u][v] * 1ll * penalty, -inf);
}
for(int u = 1; u <= n; u ++) res[u][u] = -inf;
ll ans = -inf;
for(int z = 1; z <= n; z ++){
for(int x = 1; x <= n; x ++) for(int y = 1; y <= n; y ++){
res[x][y] = max(res[x][z] + res[z][y], res[x][y]);
ans = max(ans, res[x][x]);
}
}
if(ans >= 0ll) return true;
return false;
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for(int i = 1; i <= n; i ++) for(int j = 1; j <= n; j ++){
if(i != j) dist[i][j] = inf;
else dist[i][j] = 0;
}
for(int i = 1; i <= n; i ++)
for(int j = 1; j <= k; j ++)
cin >> buy[i][j] >> sell[i][j];
for(int u, v, wt, i = 1; i <= m; i ++){
cin >> u >> v >> wt;
dist[u][v] = wt;
}
for(int z = 1; z <= n; z ++)
for(int x = 1; x <= n; x ++)
for(int y = 1; y <= n; y ++)
dist[x][y] = min(dist[x][y], dist[x][z] + dist[z][y]);
for(int x = 1; x <= n; x ++)
for(int y = 1; y <= n; y ++){
profit[x][y] = 0ll;
if(x != y)
for(int z = 1; z <= k; z ++){
if(buy[x][z] == -1 || sell[y][z] == -1) continue;
profit[x][y] = max(profit[x][y], sell[y][z] - buy[x][z]);
}
}
ll lf = 1, rg = 1000000007ll, res = 0ll;
for(int md; lf <= rg;){
md = (lf + rg) / 2;
if(check(md)){
res = md;
lf = md + 1;
}else{
rg = md - 1;
}
}
cout << res << endl;
return 0;
}
