#include<bits/stdc++.h>
using namespace std;
#define int long long
const int INF=1e18;
int n,m;
vector<int>edge[7000005];
vector<int>fedge[7000005];
int x[105],y[105];
int bx[105],by[105];
int cnt[105];
int dp[70000005];
int ret=INF;
int solve1(){
	dp[1]=0;
	for(int i=2;i<(1ll<<n);i++) dp[i]=INF;
	int sum=0;
	for(int i=1;i<(1ll<<n);i++){
		for(int j=0;j<n;j++){
			if(((i>>j)&1)&&(!(((i-1)>>j)&1))){
				sum+=y[j+1]-x[j+1];
				for(int k=0;k<edge[j+1].size();k++) cnt[edge[j+1][k]]++;
			}
			else if((((i-1)>>j)&1)&&(!((i>>j)&1))){
				sum-=y[j+1]-x[j+1];
				for(int k=0;k<edge[j+1].size();k++) cnt[edge[j+1][k]]--;
			}
			else break;
		}
		for(int j=1;j<=n;j++) if(cnt[j]&&(!((i>>(j-1))&1))) dp[i^(1<<(j-1))]=min(dp[i^(1<<(j-1))],dp[i]+max(0ll,x[j]-dp[i]-sum));
	}
	return dp[(1ll<<n)-1];
}
struct node{
	int x,y,id;
    bool operator < (const node& ano) const {
    	if(y>=0&&ano.y<0) return 1;
		else if(y<0&&ano.y>=0) return 0;
		else if(y>=0){
			if(x!=ano.x) return x<ano.x;
			else return id<ano.id;
		}
		else{
			if(x+y!=ano.x+ano.y) return x+y>ano.x+ano.y;
			else if(x!=ano.x) return x<ano.x;
			else if(y!=ano.y) return y<ano.y;
			else return id<ano.id;
		}
    }
};
int fa[105],f[105],nxt[105],ed[105];
int find(int x){
	if(fa[x]==x) return x;
	fa[x]=find(fa[x]);
	return fa[x];
}
void merge(int a,int b){
	x[a]=max(x[a],x[b]-y[a]);
	y[a]+=y[b];
}
bool vis[200005];
int calc(){
	memcpy(x,bx,sizeof x);
	memcpy(y,by,sizeof y);
	set<node>s;
	for(int i=2;i<=n;i++) s.insert((node){x[i],y[i],i});
	for(int i=1;i<=n;i++) fa[i]=i,ed[i]=i,nxt[i]=-1;]
	while(s.size()){
		int u=(*s.begin()).id;
		s.erase(*s.begin());
		int ffu=find(f[u]);
		nxt[ed[ffu]]=u;
		ed[ffu]=ed[u];
		fa[u]=ffu;
		if(ffu!=1){
			s.erase((node){x[ffu],y[ffu],ffu});
			merge(ffu,u);
			s.insert((node){x[ffu],y[ffu],ffu});
		}
	}
	int now=1,ans=0,cost=0;
	for(int i=2;i<=n;i++) vis[i]=0;
	for(int i=1;i<n;i++){
		now=nxt[now];
		vis[now]=1;
		cost+=max(x[now]-ans,0ll);
		ans+=max(x[now]-ans,0ll)+y[now];
	}
	return cost;
}
void dfs(int x){
	if(x==n+1){
		ret=min(ret,calc());
		return;
	}
	for(int i=0;i<fedge[x].size();i++){
		f[x]=fedge[x][i];
		dfs(x+1);
	}
}
int solve2(){
	memcpy(bx,x,sizeof bx);
	memcpy(by,y,sizeof by);
	for(int i=1;i<=n;i++) y[i]-=x[i],x[i]=max(x[i],y[i]);
	dfs(2);
	return ret;
}
signed main(){
	int u,v;
	cin>>n>>m;
	for(int i=2;i<=n;i++) scanf("%lld%lld",&x[i],&y[i]);
	for(int i=1;i<=m;i++){
		scanf("%lld%lld",&u,&v);
		edge[u].push_back(v);
		fedge[v].push_back(u);
	}
	if(n<=26) cout<<solve1()<<endl;
	else cout<<solve2()<<endl;
	return 0;
}

answer.code: In function ‘long long int calc()’:
answer.code:66:57: error: expected primary-expression before ‘]’ token
   66 |         for(int i=1;i<=n;i++) fa[i]=i,ed[i]=i,nxt[i]=-1;]
      |                                                         ^
answer.code: In function ‘int main()’:
answer.code:110:36: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  110 |         for(int i=2;i<=n;i++) scanf("%lld%lld",&x[i],&y[i]);
      |                               ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
answer.code:112:22: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  112 |                 scanf("%lld%lld",&u,&v);
      |                 ~~~~~^~~~~~~~~~~~~~~~~~