#include <stdio.h>
#define K 100000
#define N (K * 6)
#define MD 998244353
int min(int a, int b) { return a < b ? a : b; }
int max(int a, int b) { return a > b ? a : b; }
unsigned int Z = 12345;
int rand_() {
return (Z *= 3) >> 1;
}
int xx[N], yy[N], dd[N], ww[N], ii[N], dp[N][2], n; char trap[N], visited[N][2];
void sort(int *ii, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;
while (j < k) {
int c = dd[ii[j]] != dd[i_] ? dd[ii[j]] - dd[i_] : xx[ii[j]] - xx[i_];
if (c == 0)
j++;
else if (c < 0) {
tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
i++, j++;
} else {
k--;
tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
}
}
sort(ii, l, i);
l = k;
}
}
int solve(int x, int y, int turn) {
int d, lower, upper, i;
d = x - y;
lower = -1, upper = n;
while (upper - lower > 1) {
i = (lower + upper) / 2;
if (dd[ii[i]] < d || dd[ii[i]] == d && xx[ii[i]] < x)
lower = i;
else
upper = i;
}
if (upper == n || dd[i = ii[upper]] != d)
return 0;
x = xx[i], y = yy[i];
if (!visited[i][turn])
visited[i][turn] = 1, dp[i][turn] = trap[i] ? ww[i] : (turn == 0 ? min(solve(x + 1, y, 1), solve(x, y + 1, 1)) : max(solve(x + 1, y, 0), solve(x, y + 1, 0)));
return dp[i][turn];
}
int main() {
int n_, k, i, ans;
scanf("%*d%*d%d", &k);
n = 0;
while (k--) {
int x, y, w;
scanf("%d%d%d", &x, &y, &w);
xx[n] = x, yy[n] = y, ww[n] = w, trap[n] = 1, n++;
if (x > 1)
xx[n] = x - 1, yy[n] = y, ww[n] = 0, n++;
if (y > 1)
xx[n] = x, yy[n] = y - 1, ww[n] = 0, n++;
if (x > 2)
xx[n] = x - 2, yy[n] = y, ww[n] = 0, n++;
if (x > 1 && y > 1)
xx[n] = x - 1, yy[n] = y - 1, ww[n] = 0, n++;
if (y > 2)
xx[n] = x, yy[n] = y - 2, ww[n] = 0, n++;
}
for (i = 0; i < n; i++)
dd[i] = xx[i] - yy[i];
for (i = 0; i < n; i++)
ii[i] = i;
sort(ii, 0, n);
n_ = 0;
for (i = 0; i < n; i++)
if (n_ == 0 || xx[ii[n_ - 1]] != xx[ii[i]] || yy[ii[n_ - 1]] != yy[ii[i]])
ii[n_++] = ii[i];
else if (trap[ii[i]])
ii[n_ - 1] = ii[i];
n = n_;
ans = 0;
for (i = 0; i < n; i++)
ans = (ans + (long long) solve(xx[ii[i]], yy[ii[i]], 0) * (i == 0 || dd[ii[i]] != dd[ii[i - 1]] ? min(xx[ii[i]], yy[ii[i]]) : xx[ii[i]] - xx[ii[i - 1]])) % MD;
if (ans < 0)
ans += MD;
printf("%d\n", ans);
return 0;
}
