#include <bits/stdc++.h>
#define FOR(i, x, n) for(int i = x; i < n; i++)
#define F0R(i, n) FOR(i, 0, n)
#define ROF(i, x, n) for(int i = n - 1; i >= x; i--)
#define R0F(i, n) ROF(i, 0, n)
#define WTF cout << "WTF" << endl
#define IOS ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define F first
#define PB push_back
#define ALL(x) x.begin(), x.end()
#define RALL(x) x.rbegin(), x.rend()
using namespace std;
typedef long long LL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef pair<int, PII> PPI;
typedef vector<int> VI;
typedef vector<LL> VLL;
typedef vector<PII> VPII;
typedef vector<PLL> VPLL;
const int N = 100 + 7;
const int K = 1000 + 7;
const LL INF = 1e9 + 7;
#define B 0
#define S 1
LL n, m, k;
LL dist[N][N], obj[N][K][2], opt[N][N], adj[N][N], len[N];
void init() {
cin >> n >> m >> k;
F0R(i, n) F0R(j, k) cin >> obj[i][j][B] >> obj[i][j][S];
F0R(i, n) F0R(j, n) dist[i][j] = INF;
F0R(i, n) dist[i][i] = 0;
F0R(i, m) {
int u, v, w;
cin >> u >> v >> w;
u--; v--;
dist[u][v] = w;
}
return;
}
void precalc() {
F0R(x, n) F0R(i, n) F0R(j, n)
dist[i][j] = min(dist[i][j], dist[i][x] + dist[x][j]);
F0R(i, n) F0R(j, n) F0R(x, k) if (obj[i][x][B] != -1 && obj[j][x][S] != -1)
opt[i][j] = max(opt[i][j], - obj[i][x][B] + obj[j][x][S]);
return;
}
bool check(LL m) {
F0R(i, n) F0R(j, n) adj[i][j] = INF;
F0R(i, n) adj[i][i] = 0;
fill(len, len + n, INF);
len[0] = 0;
F0R(i, n) F0R(j, n)
if (dist[i][j] != INF) adj[i][j] = m * dist[i][j] - opt[i][j];
//cout << "adj : " << endl; F0R(i, n) F0R(j, n) cout << adj[i][j] << " \n"[j == n - 1];
F0R(go, n) F0R(i, n) F0R(j, n) if (adj[i][j] != INF)
len[j] = min(len[j], len[i] + adj[i][j]);
F0R(i, n) F0R(j, n) if (adj[i][j] != INF)
if (len[j] > len[i] + adj[i][j]) return 1;
return 0;
}
int main() {
IOS;
init();
precalc();
LL l = 0, r = 1e11, mid;
while(l < r) {
mid = (l + r) >> 1;
if (!check(mid)) r = mid;
else l = mid + 1;
}
cout << l << endl;
}
