#include<bits/stdc++.h>
#define int long long
#define mod 998244353ll
#define pii pair<int,int>
#define fi first
#define se second
#define mems(x,y) memset(x,y,sizeof(x))
#define pb push_back
#define db double
using namespace std;
const int maxn=200010;
const int inf=1e18;
inline int read(){
	int x=0,f=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+(ch-48);ch=getchar();}
	return x*f;
}
bool Mbe;

int n,m,a[maxn],ans;
int mx[maxn],se[maxn],to[maxn];
void work(){
	n=read();m=read();
	for(int i=1;i<=n;i++)a[i]=read();
	for(int i=1;i<=m;i++){
		int u=read(),v=read();
		if(mx[u]<a[v])se[u]=mx[u],mx[u]=a[v];
		else if(se[u]<a[v])se[u]=a[v];
		if(mx[v]<a[u])se[v]=mx[v],mx[v]=a[u];
		else if(se[v]<a[u])se[v]=a[u];
		to[u]=v,to[v]=u;
	}
	if(n==1)ans=a[1];
	for(int i=1;i<=n;i++){
		if(se[i])ans=max(ans,a[i]);
		else{
			if(se[to[i]]==a[i])ans=max(ans,a[i]);
		}
	}
	printf("%lld\n",ans);
}

// \
444

bool Med;
int T;
signed main(){
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	
//	ios::sync_with_stdio(0);
//	cin.tie(0);cout.tie(0);
	
//	cerr<<(&Mbe-&Med)/1048576.0<<" MB\n";
	
	T=1;
	while(T--)work();
}