#include <bits/stdc++.h>

#define el '\n'

using namespace std;

using ll = long long;

void solve() {
    int n, m;
    cin >> n >> m;
    vector<vector<int>> edge(n + 1);
    vector<int> val(n + 1, 0);
    int ans = 0;
    for (int i = 1; i<= n; i++) {
        cin >> val[i];
    }
    for (int i = 1; i <= m; i++) {
        int x, y;
        cin >> x >> y;
        edge[x].push_back(y);
        edge[y].push_back(x);
    }
    for (int i=  1; i <= n; i++) {
        vector<int> v;
        for (auto to : edge[i]) {
            v.push_back(val[to]);
        }
        sort(v.begin(), v.end());
        if (v.size() < 2)
            continue;
        ans = max(ans, max(val[i], v[v.size() - 2]));
    }  
    cout << ans << el;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int T = 1;
    // cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}