#include<bits/stdc++.h>
#define god dimasi5eks
#pragma GCC optimize("O3")
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define mod 1000000007
#define dancila 3.14159265359
#define eps 1e-9
// #define fisier 1
using namespace std;
typedef long long ll;
int n, m, k, buy[102][1002], sell[102][1002];
ll cost[102][102], cost2[102][102];
int maxdif[102][102];
void fw(ll c[102][102])
{
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]);
}
int main()
{
#ifdef fisier
ifstream f("input.in");
ofstream g("output.out");
#endif
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m >> k;
for(int i = 1; i <= n; ++i)
{
for(int j = 1; j <= k; ++j)
cin >> buy[i][j] >> sell[i][j];
}
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
cost[i][j] = (1LL<<60);
for(int i = 1; i <= m; ++i)
{
int a, b, c;
cin >> a >> b >> c;
cost[a][b] = c;
}
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
if(i != j)
for(int x = 1; x <= k; ++x)
if(buy[i][x] != -1 && sell[j][x] != -1)
maxdif[i][j] = max(maxdif[i][j], sell[j][x] - buy[i][x]);
fw(cost);
ll st = 1;
ll dr = 1000000000;
ll ans = 0;
while(st <= dr)
{
ll mid = (st + dr) / 2;
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= n; ++j)
cost2[i][j] = min(cost[i][j], (1LL<<62)/mid/2) * mid - maxdif[i][j];
fw(cost2);
bool ok = 0;
for(int i = 1; i <= n; ++i)
if(cost2[i][i] <= 0)
ok = 1;
if(ok)
ans = mid, st = mid + 1;
else
dr = mid - 1;
}
cout << ans;
return 0;
}
