#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define REP(i,a,b) for(int i=(a),_end_=(b);i<=_end_;i++)
#define DREP(i,a,b) for(int i=(a),_end_=(b);i>=_end_;i--)
#define EREP(i,u) for(int i=start[u];i;i=e[i].next)
#define fi first
#define se second
#define mkr(a,b) make_pair(a,b)
#define SZ(A) ((int)A.size())
template<class T>inline void chkmin(T &a,T b){ if(a>b)a=b;}
template<class T>inline void chkmax(T &a,T b){ if(a<b)a=b;}
inline void myassert(bool a,string s){ if(!a)cerr<<s<<endl,exit(0);}
inline int read()
{
	int s=0,f=1;char ch=getchar();
	while(!isdigit(ch) && ch!='-')ch=getchar();
	if(ch=='-')ch=getchar(),f=-1;
	while(isdigit(ch))s=s*10+ch-'0',ch=getchar();
	return ~f?s:-s;
}

const int maxn=1e5+20;

int n,m;
vector<int>ed[maxn];
int a[maxn],b[maxn];
int fa[maxn],vis[maxn],id[maxn];
ll sum[maxn],mn[maxn];

inline void init()
{
	n=read();m=read();
	REP(i,1,n)
	{
		a[i]=read();b[i]=read();
		a[i]=max(a[i]-b[i],0);
		fa[i]=id[i]=i;
		sum[i]=b[i]; mn[i]=a[i];
	}
	REP(i,1,m)
	{
		int x=read(),y=read();
		ed[x].push_back(y);
		ed[y].push_back(x);
	}
	sort(id+1,id+n+1,[](int x,int y){ return a[x]<a[y];});
}

int fin(int x){ return x==fa[x]?x:fa[x]=fin(fa[x]);}

inline void doing()
{
	REP(i,1,n)
	{
		int x=id[i]; vis[x]=1;
		for(int y:ed[x])
			if(vis[y])
			{
				int u=fin(x),v=fin(y);
				if(u==v)continue;
				fa[v]=u;
				mn[u]=min(max(mn[v]-sum[u],mn[u]),max(a[u]-sum[v],mn[v]));
				sum[u]+=sum[v];
			}
	}
	printf("%lld\n",sum[id[n]]+mn[id[n]]);
}

int main()
{
	init();
	doing();
	return 0;
}
