// Author: TrispdTit
// Date: 2024-11-14 15:46:03
//贪睡是一剂烈性毒品
#include <bits/stdc++.h>
#define endl '\n'
#define int long long
#define ll long long
using namespace std;

void solve() {
    int n, m;
    cin >> n >> m;
    vector<int> v(n + 10);
    vector<int> a(n + 10);
    for (int i = 1; i <= n ; i ++)cin >> a[i];
    if(m == 0){
        cout << a[1] << endl;
        return ;
    }
    while(m --){
        int x, y;
        cin >> x >> y;
        v[x] ++ ; v[y] ++;
    }

    vector<int> mi;
    int mx = 1;
    for (int i = 1 ; i <= n ; i ++){
        if(v[i] == 1)mi.push_back(a[i]);
        else mx = max(mx,a[i]);
    }
    if(mi.size() >= 2){
        sort(mi.begin(), mi.end());
        cout << max(mi[1],mx) << endl;
    }
    else {
        cout << mx << endl;
    }
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int t = 1;
    //cin >> t;
    while(t--) {
       solve();
    }

    return 0;
}