#include <stdio.h>
#include <string.h>
#define N 100
#define C 1000
int min(int a, int b) { return a < b ? a : b; }
int max(int a, int b) { return a > b ? a : b; }
long long cc[N][N]; int n;
int bellman_ford() {
static long long dd[N], dd_[N];
static int kk[N], kk_[N];
int r, i, j;
memset(dd, 0, n * sizeof *dd), memset(kk, 0, n * sizeof *kk);
for (r = 0; r < n; r++) {
int upd;
memcpy(dd_, dd, n * sizeof *dd), memcpy(kk_, kk, n * sizeof *kk);
upd = 0;
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
if (i != j) {
long long d = dd[i] + cc[i][j];
int k = kk[i] + 1;
if (dd_[j] > d || dd_[j] == d && kk_[j] < k)
dd_[j] = d, kk_[j] = k, upd = 1;
}
memcpy(dd, dd_, n * sizeof *dd_), memcpy(kk, kk_, n * sizeof *kk_);
if (!upd)
return 0;
}
return 1;
}
int main() {
static int bb[N][C], ss[N][C], dd[N][N], pp[N][N];
int m, c, h, i, j, k, lower, upper;
scanf("%d%d%d", &n, &m, &c);
for (i = 0; i < n; i++)
for (h = 0; h < c; h++)
scanf("%d%d", &bb[i][h], &ss[i][h]);
for (i = 0; i < n; i++) {
memset(dd[i], 0x3f, n * sizeof *dd[i]);
dd[i][i] = 0;
}
while (m--) {
int d;
scanf("%d%d%d", &i, &j, &d), i--, j--;
dd[i][j] = d;
}
for (k = 0; k < n; k++)
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
dd[i][j] = min(dd[i][j], dd[i][k] + dd[k][j]);
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
for (h = 0; h < c; h++)
if (bb[i][h] != -1 && ss[j][h] != -1)
pp[i][j] = max(pp[i][j], ss[j][h] - bb[i][h]);
lower = 0, upper = 1000000001;
while (upper - lower > 1) {
int c = (lower + upper) / 2;
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
cc[i][j] = (long long) dd[i][j] * c - pp[i][j];
if (bellman_ford())
lower = c;
else
upper = c;
}
printf("%d\n", lower);
return 0;
}
