#include<iostream>
#include<cstdio>
#include<algorithm>
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef pair<ll,pair<int,int> > P;
const int maxn=3e5+10;
P edge[maxn];
int fa[maxn];
ll a[maxn],b[maxn],cost[maxn];
void init(int n)
{
  for (int i=1;i<=n;++i)
  {
    fa[i]=i;
    cost[i]=a[i]*b[i];
  }
}
int find(int x)
{
  return fa[x]==x?x:fa[x]=find(fa[x]);
}
void unio(int x,int y,ll c)
{
  int fx=find(x),fy=find(y);
  if (fx==fy)
    return;
  fa[fx]=fy;
  a[fy]=max(c,max(a[fy],a[fx]));
  b[fy]=min(b[fy],b[fx]);
  cost[fy]=min(cost[fy]+cost[fx],a[fy]*b[fy]);
}
int main()
{
  int n,m;
  scanf("%d%d",&n,&m);
  for (int i=1;i<=n;++i)
    scanf("%lld%lld",&a[i],&b[i]);
  for (int i=0;i<m;++i)
    scanf("%d%d%lld",&edge[i].se.fi,&edge[i].se.se,&edge[i].fi);
  sort(edge,edge+m);
  init(n);
  for (int i=0;i<m;++i)
  {
    int u=edge[i].se.fi,v=edge[i].se.se,c=edge[i].fi;
    unio(u,v,c);
  }
  ll ans=0;
  for (int i=1;i<=n;++i)
    if (fa[i]==i)
      ans+=cost[i];
  printf("%lld",ans);
  return 0;
}