#include <bits/stdc++.h>

using namespace std;


using i32 = int32_t;
using i64 = long long;


using vi = vector<int>;
using pii = pair<int,int>;

const int inf = INT_MAX / 2;

i32 main() {
	ios::sync_with_stdio(false), cin.tie(nullptr);
	int n, m;
	cin >> n >> m;
	vi a(n + 1);
	for(int i = 1; i <= n; i ++) cin >> a[i];

	vi deg(n + 1);
	for(int x, y; m; m --) {
		cin >> x >> y;
		deg[x] ++, deg[y] ++;
	}

	int leaf = inf, node = -inf;

	for(int i = 1; i <= n; i ++) {
		if(deg[i] == 1) leaf = min(leaf, a[i]);
		else node = max(node, a[i]);
	}

	if(leaf == inf) cout << node << "\n";
	else if(node == -inf) cout << leaf << "\n";
	else cout << max(node, leaf);

	return 0;
}