#include<bits/stdc++.h>
#define int long long 
using namespace std;
const int N = 1e6 + 10;
const int mod = 1e9 + 7;
int a[N],zhi[N];
void solve() {
	int n, m, mx = 0, mx1 = 0, mx2 = 0;
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
		if (a[i] == mx1) {
			mx2 = max(a[i], mx2);
		}
		else {
			mx1 = max(a[i], mx1);
			mx2 = mx1;
		}
	}
	while (m--) {
		int u, v;
		cin >> u>> v;
		zhi[u]++;
		zhi[v]++;
	}
	int ans=mx2;
	for (int i = 1; i <= n; i++) {
		if (a[i] == mx1) {
			if (zhi[i] != 1)ans = mx1;
		}
	}
	cout << ans <<endl;
}
signed main() {
	int _ = 1;
//	cin >> _;
	while (_--) {
		solve();
	}
}

/*
7 7
1 1 2 3 1 2 1
1 2
2 3
1 3
2 4
2 5
5 6
5 7
*/