#include<bits/stdc++.h>
#define LL long long
#define fr(x) freopen(#x".in","r",stdin);freopen(#x".out","w",stdout);
using namespace std;
const int N=2e5+5,mod=998244353;
LL n,d[N],X[N];int A,B,fa[N];
struct node{int u,v;LL w;}e[N];
vector<node>g;
inline int getf(int x){return x==fa[x]?x:fa[x]=getf(fa[x]);}
inline LL KR()
{
	iota(fa,fa+n,0);
	sort(g.begin(),g.end(),[](node X,node Y){return X.w<Y.w;});
	int ans=0;
	for(auto [u,v,w]:g)
	{
		u=getf(u),v=getf(v);
		if(u^v) fa[v]=u,ans=(ans+w)%mod;
	}return ans;
}
namespace sol1
{
	inline void sol()
	{
		for(int i=1;i<=B;i++) g.push_back(e[i]);
		for(int i=1;i<=A;i++) for(int j=0;j+d[i]<n;j++) g.push_back({j,j+d[i],X[i]});
		cout<<KR();
	}
}
int main()
{
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);cin>>n>>A>>B;
	for(int i=1;i<=A;i++) cin>>d[i]>>X[i];
	for(int i=1,u,v,w;i<=B;i++) cin>>u>>v>>w,e[i]={u,v,w};
	if(n<=200000&&A<=10) return sol1::sol(),0;
	if(A==2&&!B)
	{
		int ans;LL cnt;
		if(X[1]>X[2]) swap(X[1],X[2]),swap(d[1],d[2]);
		ans=(n-d[1])%mod*X[1]%mod;
		cnt=max(d[1]+d[2]-n,__gcd(d[1],d[2]));
		ans=(ans+(d[1]-cnt)%mod*X[2])%mod;cout<<ans;
	}
	return 0;
}