#include <bits/stdc++.h>
#define ll long long

using namespace std;
int main(){
    int n,m;cin>>n>>m;
    vector<int>deg(n+1,0);
    vector<int>w(n+1);
    for(int i=1;i<=n;i++)cin>>w[i];
    while(m--){
        int u,v;cin>>u>>v;
        deg[u]++;
        deg[v]++;
    }
    vector<int>deg1;
    int deg2=0;
    for(int i=1;i<=n;i++){
        if(deg[i]==1)
            deg1.push_back(w[i]);
        else
            deg2=max(deg2,w[i]);
    }
    if(deg1.size()<2){
        cout<<deg2;
        return 0;
    }
    sort(deg1.begin(),deg1.end(),[](int a,int b){
        return a>b;
    });
    cout<<deg1[1];
}