#include<bits/stdc++.h>

#define int long long
#define endl '\n'
#define pii std::pair<int ,int>
#define fix(x) std::fixed << std::setprecision(x)
const int inf = 1e17 + 50, MAX_N = 1e5 + 50, mod = 998244353;

void solve() {
	int n, m;
	std::cin >> n >> m;
	std::vector<int> a(n), e(n);
	for(int i = 0; i < n; i++) {
		std::cin >> a[i];
	}

	while (m--) {
		int u, v;
		std::cin >> u >> v;
		u--, v--;
		e[u]++, e[v]++;
	}

	int res = 0;
	for(int i = 0; i < n; i++) {
		if (e[i] > 1) res = std::max(a[i], res);
	}

	std::sort(a.begin(), a.end());
	std::cout << std::max(a[n - 1], res) << endl;
}

signed main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr), std::cout.tie(nullptr);
	int Lazy_boy_ = 1;
//	std::cin >> Lazy_boy_;
	while (Lazy_boy_--) solve();
	return 0;
}
/*
7
5 3 0 0 0 0 0 0 0
4 1 1 1 0 0 0 0 0
1 0 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0 1
1 0 0 0 0 0 0 0 2
99 88 77 66 55 44 33 22 11
100 90 80 70 60 50 40 30 20
 */