#include<bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define uint unsigned
#define pii pair<int,int>
#define pll pair<ll,ll>
#define PB push_back
#define fi first
#define se second
#define For(i,j,k) for (int i=(int)(j);i<=(int)(k);i++)
#define Rep(i,j,k) for (int i=(int)(j);i>=(int)(k);i--)
#define CLR(a,v) memset(a,v,sizeof(a));
#define CPY(a,b) memcpy(a,b,sizeof(a));
using namespace std;
const int N=100005;
struct edge{
	int to,next;
}e[N*2];
int head[N],tot,n,m;
int A[N],B[N],C[N],id[N];
int fa[N],vis[N];
ll mx[N],S[N];
bool cmp(int x,int y){
	return C[x]<C[y];
}
int get(int x){
	return x==fa[x]?x:fa[x]=get(fa[x]);
}
void add(int x,int y){
	e[++tot]=(edge){y,head[x]};
	head[x]=tot;
}
int main(){
	scanf("%d%d",&n,&m);
	For(i,1,n) scanf("%d%d",&A[i],&B[i]);
	For(i,1,n) C[i]=max(0,A[i]-B[i]),id[i]=i;
	For(i,1,m){
		int x,y;
		scanf("%d%d",&x,&y);
		add(x,y); add(y,x);
	}
	sort(id+1,id+n+1,cmp);
	For(i,1,n) fa[i]=i;
	For(i,1,n){
		int x=id[i]; vis[x]=1;
		mx[x]=C[x]; S[x]=B[x];
		for (int j=head[x];j;j=e[j].next)
			if (vis[e[j].to]&&get(e[j].to)!=get(x)){
				int y=get(e[j].to);
				mx[x]=min(mx[x],mx[y]+max(0ll,C[x]-(S[y]+mx[y])));
				S[x]=S[x]+S[y]; fa[y]=x;
			}
	}
	printf("%lld",S[get(1)]+mx[get(1)]);
}