// IOI 2021
#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define ends ' '
#define die(x) return cout << x << endl, 0
#define all(v) v.begin(), v.end()
#define sz(x) (int)(x.size())
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) { cerr << ends << H; debug_out(T...); }
#define debug(...) cerr << "{" << #__VA_ARGS__ << "}:", debug_out(__VA_ARGS__)
typedef long long ll;
typedef pair<int, int> pii;
const int INF = 2e9;
const ll MOD = 1e9 + 7;
////////////////////////////////////////////////////////////////////
const int N = 1e2 + 5, K = 1e3 + 5;
int n, m, t, B[N][K], S[N][K], D[N][N], V[N][N];
ll C[N][N];
bool OK(int q) {
for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) C[i][j] = 1LL * q * D[i][j] - V[i][j];
for (int k = 1; k <= n; k++) for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) C[i][j] = min(C[i][j], C[i][k] + C[k][j]);
for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) if (i != j && C[i][j] + C[j][i] <= 0) return true;
return false;
}
int main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
mt19937 Rnd(time(0));
memset(D, 63, sizeof D);
cin >> n >> m >> t;
for (int i = 1; i <= n; i++) for (int j = 1; j <= t; j++) cin >> B[i][j] >> S[i][j];
for (int i = 1; i <= m; i++) {
int v, u, w; cin >> v >> u >> w;
D[v][u] = min(D[v][u], w);
}
for (int i = 1; i <= n; i++) D[i][i] = 0;
for (int k = 1; k <= n; k++) for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) D[i][j] = min(D[i][j], D[i][k] + D[k][j]);
for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) for (int k = 1; k <= t; k++) if (B[i][k] != -1 && S[j][k] != -1) V[i][j] = max(V[i][j], S[j][k] - B[i][k]);
int dw = 0, up = INF;
while (up - dw > 1) {
int md = (dw + up) >> 1;
if (OK(md)) dw = md;
else up = md;
}
cout << dw << endl;
return 0;
}
