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

void QAQ() {
    int n, m;
    cin >> n >> m;

    vector<int> a(n + 1);

    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }

    vector adj(n + 1, vector<int>());

    for (int i = 1, u, v; i <= m; i++) {
        cin >> u >> v;
        adj[u].push_back(v), adj[v].push_back(u);
    }

    int ans = 0;

    multiset<int, greater<>> s;

    for (int i = 1; i <= n; i++) {
        if (adj[i].size() == 1) {
            s.insert(a[adj[i][0]]);
        } else {
            ans = max(ans, a[i]);
        }
    }

    if (s.size() >= 2) {
        ans = max(ans, *next(s.begin()));
    }

    cout << ans << "\n";
}

signed main() {
    cin.tie(0) -> sync_with_stdio(0);
    int t = 1;
    // cin >> t;
    for(cout << fixed << setprecision(12); t--; QAQ());
}