#include<bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
constexpr int M=2e5+5,bas=1e9+7,mod=998244353;
int m,q,ans,f[M];ull tr[M],pw[M];
vector<array<int,3>>edge;
vector<array<int,2>>opt;
vector<int>g[M];ll n;
ll read(){
    ll x=0;char ch=getchar();
    while (!isdigit(ch)) ch=getchar();
    while (isdigit(ch)) x=x*10+ch-48,ch=getchar();
    return x;
}
int rdc(int x){return x>=mod?x-mod:x;}
int find(int x){return f[x]==x?x:find(f[x]);}
void update(int x,ull p){while (x<=n) tr[x]+=p,x+=x&-x;}
ull query(int x){ull ans=0;while (x) ans+=tr[x],x-=x&-x;return ans;}
ull gethash(int l,int r){return (query(r)-query(l-1))*pw[n-l];}
void merge(int x,int y){ x=f[x];y=f[y];
    if (g[x].size()<g[y].size()) swap(x,y);
    for (auto z:g[y]){ f[z]=x;
        update(z,pw[z]*(x-y));
        g[x].emplace_back(z);
    } g[y].clear();
}
void motherfucker(){
    ll a=read(),x=read(),b=read(),y=read();
    if (x>y) swap(a,b),swap(x,y);
    ll tmp=min(n-__gcd(a,b),n*2-a-b);
    printf("%lld\n",((n-a)%mod*x+(tmp-(n-a))%mod*y)%mod);
}
int main(){
    n=read();m=read();q=read();
    if (m==2&&q==0) return motherfucker(),0;
    for (int i=pw[0]=1;i<=n;i++) pw[i]=pw[i-1]*bas;
    for (int i=1;i<=m;i++){
        int x=read(),k=read();
        opt.push_back({k,x});
    }
    sort(opt.begin(),opt.end());
    for (int i=1;i<=q;i++){
        int x=read(),y=read(),z=read();
        edge.push_back({z,x+1,y+1});
    }
    sort(edge.begin(),edge.end()); int h1=0,h2=0;
    for (int i=1;i<=n;i++) f[i]=i,g[i]={i},update(i,pw[i]*i);
    while (h1<opt.size()||h2<edge.size())
        if (h2==edge.size()||h1<opt.size()&&opt[h1][0]<edge[h2][0]){
            const int len=opt[h1][1]; int lst=1;
            while (gethash(len+1,n)!=gethash(1,n-len)){
                int l=1,r=n-len,pos=-1;
                while (l<=r){
                    int mid=l+r>>1;
                    if (gethash(len+1,len+mid)!=gethash(1,mid))
                        pos=mid,r=mid-1;
                    else l=mid+1;
                }
                merge(pos,len+pos);  lst=pos;
                ans=rdc(ans+opt[h1][0]);
            } h1++;
        }
        else{
            if (gethash(edge[h2][1],edge[h2][1])!=gethash(edge[h2][2],edge[h2][2]))
                merge(edge[h2][1],edge[h2][2]),ans=rdc(ans+edge[h2][0]); h2++;
        }
    printf("%d\n",ans);
    return 0;
}