#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
using ll = long long;
using ld = long double;
using pii = pair<ll, ll>;
using pll = pair<ll, ll>;
using pi3 = pair<pii, ll>;
#define IOS ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define F first
#define S second
#define sz(x) x.size()
#define all(x) x.begin(), x.end()
#define pb push_back
#define minr(a, b) a = min(a, b);
#define maxr(a, b) a = max(a, b);
#define shit cout << "shit\n" << flush;
#define tl while(1&1) continue;
#define rand(l, r) uniform_ll_distribution<ll64_t>(l,r)(rng)
random_device device; default_random_engine rng(device());
const ll Mod = 1e9 + 7; //998244353;
const ll LG = 64;
const ll SQ = 500;
const ll Inf = 2e15 + 10;
const ll maxN = 1e2 + 10;
const ll maxK = 1e3 + 10;
ll n, m, k;
ll b[maxN][maxK];
ll s[maxN][maxK];
ll p[maxN][maxN];
ll e[maxN][maxN][maxN];
ll dist[maxN][maxN][maxN];
bool check(ll x) {
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
e[i][j][0] = x*dist[i][j][n]-p[i][j];
for(int i = 1; i <= n; i++)
e[i][i][0] = Inf;
for(int x = 1; x <= n; x++)
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
e[i][j][x] = min(e[i][j][x-1], e[i][x][x-1]+e[x][j][x-1]);
for(int i = 1; i <= n; i++)
if(e[i][i][n] <= 0)
return true;
return false;
}
int main() {
IOS;
cin >> n >> m >> k;
for(ll i = 1; i <= n; i++)
for(ll j = 1; j <= k; j++)
cin >> b[i][j] >> s[i][j];
for(ll i = 0; i < maxN; i++)
for(ll j = 0; j < maxN; j++)
for(ll x = 0; x < maxN; x++)
dist[i][j][x] = Inf;
for(ll i = 1; i <= m; i++) {
ll u, v, t;
cin >> u >> v >> t;
minr(dist[u][v][0], t);
}
for(ll i = 1; i <= n; i++)
dist[i][i][0] = 0;
for(ll x = 1; x <= n; x++)
for(ll i = 1; i <= n; i++)
for(ll j = 1; j <= n; j++)
dist[i][j][x] = min(dist[i][j][x-1], dist[i][x][x-1]+dist[x][j][x-1]);
for(ll i = 1; i <= n; i++)
for(ll j = 1; j <= n; j++)
if(dist[i][j][n] < 0)
tl;
for(ll i = 1; i <= n; i++)
for(ll j = 1; j <= n; j++)
for(ll x = 1; x <= k; x++)
if(b[i][x] != -1 and s[j][x] != -1)
maxr(p[i][j], s[j][x]-b[i][x]);
ll ans = -Inf;
for(int i = 2; i <= n; i++)
maxr(ans, p[1][i]/(dist[1][i][n]+dist[i][1][n]));
if(ans == -Inf)
ans = 0;
for(ll i = ans+1; i <= 1e18; i*=2) {
if(check(i)) {
cout << -1;
return 0;
}
}
cout << ans;
return 0;
// for(ll i = 1; i <= n; i++)
// p[i][i] = -Inf;
ll l = 0;
ll r = 1e18;
while(l+1 < r) {
ll mid = (l+r)>>1;
if(check(mid))
l = mid;
else
r = mid;
}
cout << l;
}
