#include<bits/stdc++.h>
#define endl '\n'
#define ll  long long
#define Int __int128
#define pb push_back
#define eb emplace_back
#define MAX_LOG 21
#define ff first
#define ss second
#define M (int)1e4+10
#define ull unsigned long long
#define MAX_LOG 21
//#define double long double
using namespace std;
const double PI=3.1415926535897932385;
const int IIMIN=-2147483648;
//const ll p=998244353;
const ll mod=1e9+7;
const int INF=0x3f3f3f3f;
typedef pair<ll,ll> PLL;
typedef pair<double,double>PFF;
ll gcd(ll a,ll b)
{
    if(b) while((a%=b)&&(b%=a));
    return a+b;
}//最大公约数函数
ll spid(ll a,ll b,ll p)
{
    ll ans=1;
    while(b)
    {
        if(b&1)ans=ans*a%p;
        b>>=1;
        a=a*a%p;
    }
    return ans;
}//快速幂函数
///小香猪的代码块·香香猪猪惹人怜~
///秋雨想睡觉
const ll N =4e5+10;
ll a[N];
ll du[N];
vector<ll>go[N];
ll min_=0;
void bfs(ll u)
{
    if(du[u]>=2)return;
    for(auto i:go[u])
    {
        for(auto j:go[i])
        {
            if(j==i||j==u)continue;
            if(du[j]<2)
            {
                min_=max(min_,min(a[u],a[j]));
//                cout<<"saf"<<u<<' '<<j<<'\n';
            }
        }
    }
}
void solve()
{
    ll n,m;cin>>n>>m;
    for(int i=1;i<=n;i++)cin>>a[i];
    while(m--)
    {
        ll u,v;cin>>u>>v;
        du[u]++;du[v]++;
        go[u].eb(v);
        go[v].eb(u);
    }
    ll max_=0;
    vector<ll>vec;
    for(int i=1;i<=n;i++)
    {
        if(du[i]>=2)max_=max(a[i],max_);
    }
    for(int i=1;i<=n;i++)
        if(du[i]<2)bfs(i);
    cout<<max(max_,min_);
//    cout<<max_<<' '<<min_<<'\n';
}
///秋雨睡觉了
//7 7
//1 1 2 3 1 2 1
//1 2
//2 3
//1 3
//2 4
//2 5
//5 6
//5 7
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int t=1;
//    cin>>t;
    while(t--)
    {
        solve();
    }
}
///记忆是梦的开场白
/*
  */