// ~Be name khoda~ //
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
#define mp make_pair
#define all(x) x.begin(), x.end()
#define fi first
#define se second
#define cl clear
#define endll '\n'
const int maxn = 110;
const int maxk = 2e3 + 10;
const int maxnt = 1.2e6 + 10;
const int maxn3 = 1e3 + 10;
const int mod = 1e9 + 7;
const ll inf = 1e9 + 10;
const ll inf2 = 2e18;
ll dp[2][maxn][maxn];
ll dis[maxn][maxn], val[maxn][maxn];
ll s[maxn][maxk], b[maxn][maxk];
int n, m, k;
inline bool check(ll avg){
for(int i = 0; i < n; i++) for(int j = 0; j < n; j++){
if(i == j) dp[1][i][j] = 1;
else
dp[1][i][j] = dis[i][j] == inf ? inf2 : dis[i][j] * avg - val[i][j];
}
for(int i = 0; i < n; i++) for(int a = 0; a < n; a++) for(int b = 0; b < n; b++){
if(i != a && i != b)
dp[i%2][a][b] = min({inf2, dp[(i + 1)%2][a][b], dp[(i + 1)%2][a][i] + dp[(i + 1)%2][i][b]});
else
dp[i%2][a][b] = dp[(i + 1)%2][a][b];
}
ll mn = 1;
for(int i = 0; i < n; i++)
mn = min(mn, dp[(n - 1)%2][i][i]);
return mn <= 0;
}
int main()
{
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
cin >> n >> m >> k;
for(int i = 0; i < n; i++){
for(int j = 0; j < k; j++) cin >> b[i][j] >> s[i][j];
}
memset(dp, 60, sizeof dp);
for(int i = 0; i < m; i++){
int a, b, len; cin >> a >> b >> len;
a--; b--;
dp[1][a][b] = len;
}
for(int i = 0; i < n; i++) dp[1][i][i] = 0;
for(int i = 0; i < n; i++) for(int a = 0; a < n; a++) for(int b = 0; b < n; b++)
dp[i%2][a][b] = min({inf, dp[(i + 1)%2][a][b], dp[(i + 1)%2][a][i] + dp[(i + 1)%2][i][b]});
for(int i = 0; i < n; i++) for(int j = 0; j < n; j++){
dis[i][j] = min(inf, dp[(n - 1)%2][i][j]);
if(i != j) for(int r = 0; r < k; r++) if(min(s[j][r], b[i][r]) != -1)
val[i][j] = max(val[i][j], s[j][r] - b[i][r]);
}
ll lo = 0, hi = inf;
while(hi - lo > 1){
ll mid = (lo + hi) >> 1;
if(check(mid)) lo = mid;
else hi = mid;
}
cout << lo << endl;
}
