#include<bits/stdc++.h>
#define int long long
using namespace std;
int read()
{
	int x = 0, f = 1;
	char c = getchar();
	while(c != EOF and !isdigit(c))
	{
		if(c == '-')f = -1;
		c = getchar();
	}
	while(isdigit(c))
	{
		x = x * 10 + c - '0';
		c = getchar();
	}
	return x * f;
}
int n, m, d[1000010], a[100010];
signed main()
{
	int T = 1;
	while(T --)
	{
		n = read();
		m = read();
		int ans = 0, ans1 = 0x3f3f3f3f;
		for(int i = 1;i <= n;i ++)
		{
			a[i] = read();
		}
		for(int i = 1;i<= m;i ++)
		{
			int u = read(), v = read();
			d[u] ++;
			d[v] ++;
		}
		for(int i = 1;i<= n;i ++)
		{
			if(d[i] >= 2)ans = max(ans, a[i]);
			else ans1 = min(ans1, a[i]);
		}
		if(ans1 == 0x3f3f3f3f)ans1 = 0;
		cout<<max(ans, ans1)<<'\n';
	}
	return 0;
}