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

#define int long long



void solve() {
    int n, m;
    cin >> n >> m;
    vector<int> a(n + 1), deg(n + 1);
    for(int i = 1; i <= n; ++i)
        cin >> a[i];
    for(int i = 0; i < m; ++i) {
        int u, v;
        cin >> u >> v;
        ++deg[u];
        ++deg[v];
    }
    if(n == 1) {
        cout << a[1] << "\n";
        return ;
    }
    vector<int> x, y;
    for(int i = 1; i <= n; ++i) {
        if(deg[i] >= 2)
            x.emplace_back(a[i]);
        else
            y.emplace_back(a[i]);
    }
    sort(x.begin(), x.end());
    sort(y.begin(), y.end(), greater());
    int ans = x.back();
    if(y.size() >= 2)
        ans = max(ans, y[1]);
    cout << ans << '\n';
}

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

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

    return 0;
}

/*

7 7 
1 1 2 3 1 2 1
1 2
2 3
1 3
2 4
2 5
5 6
5 7


*/