#include<bits/stdc++.h>
using namespace std;
#define int long long
const int INF=1e18;
int n,m;
vector<int>edge[7000005];
int x[105],y[105];
int cnt[105];
int dp[70000005];
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];
}
int solve2(){
	return -1;
}
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);
	}
	cout<<solve1()<<endl;
	return 0;
}