#include <bits/stdc++.h>
#define int long long
using namespace std;
const int INF = 2e18;
const int MOD = 998244353;
const int N = 3e5+10;
const double eps = 1e-8;
int t,m,n,k;
int d[N];
int arr[N];
signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        cin>>arr[i];
    }
    int ans = 0;
    int u,v;
    for(int i=1;i<=m;i++){
        cin>>u>>v;
        d[u]++;
        d[v]++;
    }
    if(n==1){
        cout<<arr[1]<<"\n";
        return 0;
    }
    vector<int> key;
    for(int i=1;i<=n;i++){
        if(d[i]==1){
            key.push_back(arr[i]);
        }else{
            ans = max(ans,arr[i]);
        }
    }
    sort(key.begin(),key.end());
    int tmp = min(key[key.size()-1],key[key.size()-2]);
    ans = max(ans,tmp);
    cout<<ans<<"\n";
    return 0;
}