// Author: TrispdTit
// Date: 2024-11-14 17:47:50
//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> w(n + 1);
    vector<vector<int>> adj(n + 1, vector<int>());

    int fmn = 1e9;
    for(int i = 1; i <= n; i++) {
        cin >> w[i];
    }
    for(int i = 1, u, v; i <= m; i++) {
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for(int i = 1; i <= n; i++) {
        if(adj[i].size() <= 1) fmn = min(w[i], fmn);
    }

    vector<int> id(n + 1, 0);
    iota(id.begin(), id.end(), 0);
    sort(id.begin() + 1, id.end(), [&](int i, int j) {
        return w[i] < w[j];
    });

    int res = 0;
    for(int i = n; i >= 1; i--) {
        if(adj[id[i]].size() >= 2) {
            res = w[id[i]];
            break;
        }
    }

    if(fmn != 1e9) {
        res = max(res, fmn);
    }

    cout << res << "\n";
}

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

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

    return 0;
}