#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for(int i=a;i<n;++i)
#define per(i,a,n) for(int i=n-1;i>=a;--i)
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define endl '\n'
#define SZ(x) ((ll)(x).size())
typedef vector<int> vi;
typedef vector<long long> vl;
typedef long long ll;
typedef pair<int,int> pii;
typedef double db;
mt19937 mrand(random_device{}());
int rnd(int x){return mrand()%x;}
const ll mod=998244353;

signed main() {
	int n,m;
	scanf("%d%d",&n,&m);
	vi val(n+1),du(n+1);
	rep(i,1,n+1) scanf("%d",&val[i]);
	multiset<int> p[n+1];
	rep(i,0,m) {
		int u,v;
		scanf("%d%d",&u,&v);
		p[u].insert(val[v]);
		p[v].insert(val[u]);
		du[u]++,du[v]++;
	}
	if (n==1) {
		printf("%d",val[1]);
		return 0;
	}
	int ans=0;
	rep(i,1,n+1) {
		if (SZ(p[i])>=4) {
			auto it1=p[i].rbegin();
			auto it2=it1;
			it2--;
			ans=max(val[i],min(*it1,*it2));
		}
	}
	printf("%d",ans);
	return 0;
}