#include <bits/stdc++.h>
using namespace std;
#define N 2001000
struct node {
	int x,y;
}a[N];
int n,cc,cnt,ans;
int h[N],f[N];
int get(int x) {return x==f[x] ? x : f[x]=get(f[x]);}
int main()
{
	scanf("%d",&n);
	for (int i=1;i<=n;i++) scanf("%d%d",&a[i].x,&a[i].y),h[++cc]=a[i].x,h[++cc]=a[i].y;
	sort(h+1,h+cc+1);
	cnt=unique(h+1,h+cc+1)-h-1;
	for (int i=1;i<=n;i++) {
		a[i].x=lower_bound(h+1,h+cnt+1,a[i].x)-h;
		a[i].y=lower_bound(h+1,h+cnt+1,a[i].y)-h;
	}
	for (int i=1;i<=cnt;i++) f[i]=i;
	for (int i=1;i<=n;i++) {
		int x=a[i].x,y=a[i].y;
		x=get(x); y=get(y);
		if (!x && !y) {
			puts("-1");
			return 0;
		}
		//cout<<x<<" "<<y<<endl;
		if (x>y) swap(x,y);
		//形成环的情况，第二种情况就是选择小的，大的作为结尾点
		if (x==y || !x || !y) ans=max(ans,max(h[x],h[y])),f[x]=f[y]=0;
		else ans=max(ans,min(h[x],h[y])),f[x]=y;
	}
	printf("%d\n",ans);
	return 0;
}