#include <bits/stdc++.h>
using namespace std;
using i64 = long long;

void solve() {
    int n, m;
    cin >> n >> m;
    vector<int> a(n + 1);
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    if (n == 1) {
        cout << "1\n";
        return;
    }
    vector<vector<int>> adj(n + 1);
    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        adj[a].emplace_back(b);
        adj[b].emplace_back(a);
    }
    vector<int> pos;
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        if (adj[i].size() == 1) {
            pos.emplace_back(a[i]);
        } else {
            ans = max(ans, a[i]);
        }
    }
    sort(pos.begin(), pos.end(), greater<>());
    ans = max(ans, pos[1]);

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

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

    int t = 1;
    // cin >> t;

    while (t--) {
        solve();
    }

    return 0;
}