#include <bits/stdc++.h>
#define va first
#define vb second
#define lb lower_bound
#define ub upper_bound
#define bs binary_search
#define pp push_back
#define ep emplace_back
#define all(v) (v).begin(),(v).end()
#define szz(v) ((int)(v).size())
#define bi_pc __builtin_popcount
#define bi_pcll __builtin_popcountll
#define bi_tz __builtin_ctz
#define bi_tzll __builtin_ctzll
#define fio ios_base::sync_with_stdio(0);cin.tie(0);
#ifdef TAMREF
#define debug(...) fprintf(stderr, __VA_ARGS__)
#else
#define debug(...) 42
#endif
using namespace std;
using ll = long long; using lf = long double;
using pii = pair<int,int>; using ppi = pair<int,pii>;
using pll = pair<ll,ll>; using pff = pair<lf,lf>;
using ti = tuple<int,int,int>;
using base = complex<double>;
const lf PI = 3.14159265358979323846264338L;
template <typename T>
inline T umax(T& u, T v){return u = max(u, v);}
template <typename T>
inline T umin(T& u, T v){return u = min(u, v);}
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
int n, m, k;
const ll inf = 1e15;
ll sp[105][105], rv[105][105];
pll tsp[105][105];
vector<ll> B[105], S[105];
pll operator+ (pll u, const pll v){
return pll(u.va + v.va, u.vb + v.vb);
}
bool pro(ll x){
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
if(i == j){
tsp[i][i] = pll(0,0);
continue;
}
tsp[i][j] = pll(sp[i][j] * x - rv[i][j], -sp[i][j]);
}
}
for(int t = 1; t <= n; t++){
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
tsp[i][j] = min(tsp[i][j], tsp[i][t] + tsp[t][j]);
}
}
}
debug("-------tsp------x = %lld----\n",x);
for(int i = 1; i <= n; i++){
for(int j =1 ; j <= n; j++){
debug("(%lld,%lld) ",tsp[i][j].va,tsp[i][j].vb);
}
debug("\n");
}
return tsp[1][1] < pll(0,0);
}
int main(){
fio;
cin >> n >> m >> k;
for(int i = 1; i <= n; i++){
fill(sp[i] + 1, sp[i] + n + 1, inf);
sp[i][i] = 0;
B[i] = vector<ll>(k + 1);
S[i] = vector<ll>(k + 1);
for(int j = 1; j <= k; j++){
cin >> B[i][j] >> S[i][j];
}
}
for(ll i = 1, a, b, w; i <= m; i++){
cin >> a >> b >> w;
sp[a][b] = min(w, sp[a][b]);
}
for(int k = 1; k <= n; k++){
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
sp[i][j] = min(sp[i][j], sp[i][k] + sp[k][j]);
}
}
}
debug("-------sp----------\n");
for(int i = 1; i <= n; i++){
for(int j =1 ; j <= n; j++){
debug("%lld ",sp[i][j]);
}
debug("\n");
}
for(int i = 1; i <= n; i++){
for(int j = 1; j <= n; j++){
for(int t = 0; t <= k; t++){
if(B[i][t] == -1 || S[j][t] == -1) continue;
rv[i][j] = max(rv[i][j], S[j][t] - B[i][t]);
}
}
}
ll lo = 0, mi, hi = 2e9;
while(lo < hi){
mi = (lo + hi + 1) >> 1;
if(pro(mi)) lo = mi;
else hi = mi - 1;
}
cout << lo << '\n';
}
