#include<bits/stdc++.h>

typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;
typedef double lf;
typedef long double llf;
typedef std::pair<int,int> pii;

#define xx first
#define yy second

template<typename T> inline T max(T a,T b){return a>b?a:b;}
template<typename T> inline T min(T a,T b){return a<b?a:b;}
template<typename T> inline T abs(T a){return a>0?a:-a;}
template<typename T> inline bool repr(T &a,T b){return a<b?a=b,1:0;}
template<typename T> inline bool repl(T &a,T b){return a>b?a=b,1:0;}
template<typename T> inline T gcd(T a,T b){T t;if(a<b){while(a){t=a;a=b%a;b=t;}return b;}else{while(b){t=b;b=a%b;a=t;}return a;}}
template<typename T> inline T sqr(T x){return x*x;}
#define mp(a,b) std::make_pair(a,b)
#define pb push_back
#define I inline
#define mset(a,b) memset(a,b,sizeof(a))
#define mcpy(a,b) memcpy(a,b,sizeof(a))

#define fo0(i,n) for(int i=0,i##end=n;i<i##end;i++)
#define fo1(i,n) for(int i=1,i##end=n;i<=i##end;i++)
#define fo(i,a,b) for(int i=a,i##end=b;i<=i##end;i++)
#define fd0(i,n) for(int i=(n)-1;~i;i--)
#define fd1(i,n) for(int i=n;i;i--)
#define fd(i,a,b) for(int i=a,i##end=b;i>=i##end;i--)
#define foe(i,x)for(__typeof(x.end())i=x.begin();i!=x.end();++i)

struct Cg{I char operator()(){return getchar();}};
struct Cp{I void operator()(char x){putchar(x);}};
#define OP operator
#define RT return *this;
#define RX x=0;char t=P();while((t<'0'||t>'9')&&t!='-')t=P();bool f=0;\
if(t=='-')t=P(),f=1;x=t-'0';for(t=P();t>='0'&&t<='9';t=P())x=x*10+t-'0'
#define RL if(t=='.'){lf u=0.1;for(t=P();t>='0'&&t<='9';t=P(),u*=0.1)x+=u*(t-'0');}if(f)x=-x
#define RU x=0;char t=P();while(t<'0'||t>'9')t=P();x=t-'0';for(t=P();t>='0'&&t<='9';t=P())x=x*10+t-'0'
#define TR *this,x;return x;
I bool IS(char x){return x==10||x==13||x==' ';}template<typename T>struct Fr{T P;I Fr&OP,(int&x)
{RX;if(f)x=-x;RT}I OP int(){int x;TR}I Fr&OP,(ll &x){RX;if(f)x=-x;RT}I OP ll(){ll x;TR}I Fr&OP,(char&x)
{for(x=P();IS(x);x=P());RT}I OP char(){char x;TR}I Fr&OP,(char*x){char t=P();for(;IS(t);t=P());if(~t){for(;!IS
(t)&&~t;t=P())*x++=t;}*x++=0;RT}I Fr&OP,(lf&x){RX;RL;RT}I OP lf(){lf x;TR}I Fr&OP,(llf&x){RX;RL;RT}I OP llf()
{llf x;TR}I Fr&OP,(uint&x){RU;RT}I OP uint(){uint x;TR}I Fr&OP,(ull&x){RU;RT}I OP ull(){ull x;TR}};Fr<Cg>in;
#define WI(S) if(x){if(x<0)P('-'),x=-x;char s[S],c=0;while(x)s[c++]=x%10+'0',x/=10;while(c--)P(s[c]);}else P('0')
#define WL if(y){lf t=0.5;for(int i=y;i--;)t*=0.1;if(x>=0)x+=t;else x-=t,P('-');*this,(ll)(abs(x));P('.');if(x<0)\
x=-x;while(y--){x*=10;x-=floor(x*0.1)*10;P(((int)x)%10+'0');}}else if(x>=0)*this,(ll)(x+0.5);else *this,(ll)(x-0.5);
#define WU(S) if(x){char s[S],c=0;while(x)s[c++]=x%10+'0',x/=10;while(c--)P(s[c]);}else P('0')
template<typename T>struct Fw{T P;I Fw&OP,(int x){WI(10);RT}I Fw&OP()(int x){WI(10);RT}I Fw&OP,(uint x){WU(10);RT}
I Fw&OP()(uint x){WU(10);RT}I Fw&OP,(ll x){WI(19);RT}I Fw&OP()(ll x){WI(19);RT}I Fw&OP,(ull x){WU(20);RT}I Fw&OP()
(ull x){WU(20);RT}I Fw&OP,(char x){P(x);RT}I Fw&OP()(char x){P(x);RT}I Fw&OP,(const char*x){while(*x)P(*x++);RT}
I Fw&OP()(const char*x){while(*x)P(*x++);RT}I Fw&OP()(lf x,int y){WL;RT}I Fw&OP()(llf x,int y){WL;RT}};Fw<Cp>out;

const int N=10007,M=2333333;

struct edge
{
	int to;edge*ne;
}_e[M],*e=_e,*p[M];

inline void add(int a,int b)
{
	*e=(edge){b,p[a]};p[a]=e++;
}

int n,m,bc,sm,tm,x[N],y[N],v[N*2],o[N*2],f[1<<16],dfn[M],low[M],st[M],bl[M];

inline pii get(int l,int r)
{
	return mp(std::lower_bound(v,v+n*2,l)-v+1,std::upper_bound(v,v+n*2,r)-v);
}

inline void build(int x,int l,int r)
{
	if(l==r)f[x]=o[l];
	else
	{
		f[x]=0;
		int t=(l+r)>>1;
		build(x<<1,l,t);
		build(x<<1|1,t+1,r);
	}
}

inline int qry(int x,int l,int r,int ql,int qr)
{
	if(l>=ql&&r<=qr&&f[x])return f[x];
	int t=(l+r)>>1,s=++m;
	if(ql<=t)add(qry(x<<1,l,t,ql,qr),s);
	if(qr>t)add(qry(x<<1|1,t+1,r,ql,qr),s);
	if(l>=ql&&r<=qr)f[x]=s;
	return s;
}

inline void dfs(int x)
{
	dfn[x]=low[x]=++tm;
	st[sm++]=x;
	for(edge*i=p[x];i;i=i->ne)
	{
		if(!dfn[i->to])
		{
			dfs(i->to);
			repl(low[x],low[i->to]);
		}
		else if(!bl[i->to])
		{
			repl(low[x],dfn[i->to]);
		}
	}
	if(low[x]==dfn[x])
	{
		for(bc++;;)
		{
			bl[st[--sm]]=bc;
			if(st[sm]==x)break;
		}
	}
}

inline bool chk(int l)
{
	build(1,1,n*2);
	m=n*2;
	fo1(i,n)
	{
		pii t;
		t=get(v[x[i]-1]-l+1,v[x[i]-1]+l-1);
		//out,'\n';out,t.xx,' ',x[i],' ',t.yy,'\n';
		if(t.xx!=x[i])add(qry(1,1,n*2,t.xx,x[i]-1),i+n);
		if(x[i]!=t.yy)add(qry(1,1,n*2,x[i]+1,t.yy),i+n);
		t=get(v[y[i]-1]-l+1,v[y[i]-1]+l-1);
		//out,t.xx,' ',y[i],' ',t.yy,'\n';
		if(t.xx!=y[i])add(qry(1,1,n*2,t.xx,y[i]-1),i);
		if(y[i]!=t.yy)add(qry(1,1,n*2,y[i]+1,t.yy),i);
	}
	fo1(i,m)if(!dfn[i])dfs(i);
	bool res=1;
	fo1(i,n)res&=bl[i]!=bl[i+n];
	fo1(i,m)p[i]=0;
	fo1(i,m)dfn[i]=low[i]=bl[i]=0;
	e=_e;
	bc=tm=0;
	return res;
}

int main()
{
	in,n;
	fo1(i,n)in,x[i],y[i];
	fo1(i,n)v[i-1]=x[i],v[i+n-1]=y[i];
	std::sort(v,v+n*2);
	fo1(i,n)x[i]=std::upper_bound(v,v+n*2,x[i])-v;
	fo1(i,n)y[i]=std::upper_bound(v,v+n*2,y[i])-v;
	fo1(i,n)x[i]-=f[x[i]]++;
	fo1(i,n)y[i]-=f[y[i]]++;
	//fo1(i,n)out,x[i],' ';out,'\n';
	//fo1(i,n)out,y[i],' ';out,'\n';
	fo1(i,n)o[x[i]]=i,o[y[i]]=i+n;
	int l=0,r=1e9;
	while(l+1<r)
	{
		int mid=(l+r)>>1;
		if(chk(mid))l=mid;
		else r=mid;
	}
	out,l,'\n';
}

Measured memory_bytes: 74624