#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e6 + 100;
const int mod = 1e9 + 7;
vector<int> e[N];
int a[N];
void solve() {
	int n, m;
	cin >> n >> m;
	for(int i = 1; i <= n; i++) cin >> a[i];
	for(int i = 1; i <= m; i++) {
		int x, y;
		cin >> x >> y;
		e[x].push_back(a[y]);
		e[y].push_back(a[x]);
	}
	if(n == 1) {
		cout << a[1] << endl;
		return;
	}
	int maxn = 0;
	for(int i = 1; i <= n; i++) {
		sort(e[i].begin(), e[i].end());
		if(e[i].size() < 2) continue;
		int len = e[i].size();
		int x = e[i][len - 1], y = e[i][len - 2];
		int ans = max(a[i], min(x, y));
		maxn = max(maxn, ans);
	}
	cout << maxn << endl;
}
signed main() {
	int t = 1;
	//cin >> t;
	while(t--) solve();
}