#include <bits/stdc++.h>
using namespace std;

using ui = unsigned;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define rep(i,l,r) for(int i=(l);i<=(r);++i)
#define per(i,l,r) for(int i=(l);i>=(r);--i)
#define repn(i,n) for(int i=0;i<(n);++i)
#define sizc(x) ((int)(x).size())
#define allc(x) (x).begin(),(x).end()
#define fir first
#define sec second

constexpr int N = 1e5+5;

int n,m;
int a[N];
vector<int> G[N];

signed main(){
	// freopen(".in","r",stdin);
	// freopen(".out","w",stdout);
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

    cin>>n>>m;
    rep(i,1,n)cin>>a[i];
    rep(i,1,m){
        int u,v;cin>>u>>v;
        G[u].push_back(v);
        G[v].push_back(u);
    }
    if(n==1){
        cout<<a[1]<<'\n';
        return 0;
    }
    int ans=0;
    rep(i,1,n)if(G[i].size()>1){
        vector<int> vc;
        for(auto j:G[i])vc.push_back(a[j]);
        sort(allc(vc),greater<int>());
        ans=max(ans,max(a[i],vc[1]));
    }
    cout<<ans<<'\n';
}