// Zende bad Shoma nasime faghat !
#include <bits/stdc++.h>
#define pb push_back
#define F first
#define Se second
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " : " << x << '\n'
using namespace std;
typedef __int128 ll;
typedef long double ld;
typedef string str;
typedef pair<ll, ll> pll;
const ll Mod = 1000000007LL;
const int N = 1e2 + 10;
const int K = 1e3 + 10;
const ll Inf = 2242545357980376863LL;
const ll Log = 30;
int n, m, k;
int B[N][K], S[N][K];
ll dis[N][N], d[N][N];
int pro[N][N];
ll mul(ll A, ll B){
if((Inf + A - 1) / A <= B){
assert(false);
return Inf;
}
return A * B;
}
bool Check(ll x){
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
d[i][j] = (i == j ? Inf : x * dis[i][j] - pro[i][j]);
for(int z = 1; z <= n; z++)
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
d[i][j] = min(d[i][j], d[i][z] + d[z][j]);
for(int i = 1; i <= n; i++)
if(d[i][i] <= 0)
return true;
return false;
}
int main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
memset(dis, 31, sizeof dis);
cin >> n >> m >> k;
for(int i = 1; i <= n; i++)
for(int j = 1; j <= k; j++)
cin >> B[i][j] >> S[i][j];
int u, v, w;
for(int i = 1; i <= m; i++){
cin >> u >> v >> w;
dis[u][v] = min(dis[u][v], (ll) w);
}
// Floyd
for(int i = 1; i <= n; i++) dis[i][i] = 0;
for(int z = 1; z <= n; z++)
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
dis[i][j] = min(dis[i][j], dis[i][z] + dis[z][j]);
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
for(int obj = 1; obj <= k; obj ++)
if((S[j][obj] != -1) && (B[i][obj] != -1))
pro[i][j] = max(pro[i][j], S[j][obj] - B[i][obj]);
int L = 0, R = 1e9 + 1, mid;
while(L + 1 < R){
mid = (L + R) >> 1;
if(Check(mid)) L = mid;
else R = mid;
}
cout << L << '\n';
return 0;
}
