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#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#define X 20005
#define ll long long
#define maxn 100050 
using namespace std;
inline int Max(int a,int b)
{
	return a>b?a:b;
}
inline int scan()
{
    register int x=0;
    register char c=getchar();
    bool f=0;
    while(c<'0'||c>'9')c=='-'?f=1:f,c=getchar();
    while(c>='0'&&c<='9')x=(x<<1)+(x<<3)+(c^48),c=getchar();
    return f?-x:x;
}
inline void print(int k,char ch=0)
{
    if(k<0)k=-k,putchar('-');
    if(k>=10)print(k/10,0);
    putchar(k%10+'0');
    if(ch)putchar(ch);
}
int n,match[3000010],a,b,total,ans,head[3000010],T,cnt,temp;
struct EDGE
{
	int to,Next,w;
	bool operator < (const EDGE &b)const {return this->w<b.w;}
	bool operator <= (const EDGE &b)const {return this->w<=b.w;}
	bool operator > (const EDGE &b)const {return this->w>b.w;}
	bool operator >= (const EDGE &b)const {return this->w>=b.w;}
}edge[40000000];
inline void add_edge(int u,int v)
{
	total++;
	edge[total].Next=head[u];
	edge[total].to=v;
	head[u]=total;
}
int MM=0;
bool book[1000050];
inline bool dfs(int s)
{
	if (s==-1) return false;
	int e=head[s],Next;
	while (e)
	{
		Next=edge[e].to;
		MM=Max(MM,Next);
		if (!book[Next])
		{
			book[Next]=true;
			if (!match[Next]||dfs(match[Next]))
			{
				match[Next]=s;
				return true;
			}
		}
		e=edge[e].Next;
	}
	return false;
}
int main()
{
	n=scan();
	for (int i=1;i<=n;i++)
	{
		a=scan();b=scan();
		add_edge(a,i);
		add_edge(b,i);
	}
	for (int i=1;i<=10000;i++)
	{
		memset(book,false,sizeof(book));//用memset把book数组全部清空不会tle 
		//fill(book+1,book+1+MM,false);//但是用 fill这么刷数组会 t4个点 
		//MM 是遍历过程中 经过的最大的点 
		MM=0;
		if (!dfs(i))
		{
			printf("%d",i-1);
			return 0;
		}
	}
	printf("10000");
	return 0;
}