#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define fi first
#define in inline
#define se second
#define mp make_pair
#define pb push_back
const int N = 1e6+10;
const ll mod = 998244353;

ll read(){
	ll x = 0,f = 1;char c = getchar();
	for(;c < '0' || c > '9';c = getchar())if(c == '-')f = -1;
	for(;c >= '0' && c <= '9';c = getchar())x = (x<<1) + (x<<3) + c-'0';
	return x * f;
}



int n,m,q;

ll ksm(ll x,ll y){
	ll ans = 1;
	while(y){
		if(y & 1)ans = ans * x % mod;
		x = x * x % mod,y >>= 1; 
	}return ans;
}
int s[N];
int main(){
	freopen("plusminus.in","r",stdin);
	freopen("plusminus.out","w",stdout);
	n = read(),m = read(),q = read();
	bool f = 0;
	if(n < m)swap(n,m),f = 1;
	for(int i = 1;i <= q;i++){
		int x = read(),y = read(),op = read();
		if(f)swap(x,y);
		s[x]++;
	}
	if((n & 1) + (m & 1) == 1)return printf("0\n"),0;
	ll ans = 1;
	for(int i = 1;i <= n;i++)ans = ans * ksm(2ll,(m - s[i] + 1) / 2) % mod;
	printf("%lld\n",ans * ksm(ksm(2ll,m),mod - 2) % mod);

	return 0;

}