#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define re(i,a,b) for(int i=(a);i<(b);i++)
#define repd(i,a,b) for(int i=(a);i>=(b);i--)
#define run(v) for(int k=head[v];k;k=e[k].ne)
#define v e[k].t
#define clr(a) memset(a,0,sizeof(a));
#define il inline
#define sz(a) ((int)a.size())
#define all(a) a.begin(),a.end()
#define mp make_pair
#define pb push_back 
#define w1 first
#define w2 second
#define adm(a,b,c) {a=a+b;if(a>=c)a-=c;else if(a<0)a+=c;}
typedef pair<int,int> pa;
typedef long long ll;typedef long double ld;typedef unsigned long long ull;
const int N=5e6+5,M=5e7+5,INF=1e9,mod=1e9+7;
const ll linf=1e18;const double eps=1e-8,pi=acos(-1);
il int gmin(int &a,int b){if(a>b)a=b;}il ll gmin(ll &a,ll b){if(a>b)a=b;}il int gmax(int &a,int b){if(a<b)a=b;}il ll gmax(ll &a,ll b){if(a<b)a=b;}
il void read(ll&x){ll f=1,t=0;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){t=t*10+ch-'0';ch=getchar();}x=t*f;}il ll read(ll&x,ll&y){read(x);read(y);}
il void read(int&x){int f=1,t=0;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){t=t*10+ch-'0';ch=getchar();}x=t*f;}il int read(int&x,int&y){read(x);read(y);}
il void read(int&a,int&b,int&c){read(a);read(b);read(c);}il void read(ll&a,ll&b,ll&c){read(a);read(b);read(c);}
il int read(){int x;read(x);return x;}
il ll qpow(ll a,ll b,ll p){ll ret=1;for(;b;b>>=1,a=a*a%p)if(b&1)ret=ret*a%p;return ret;}il ll qpow(ll a,ll b){ll ret=1;for(;b;b>>=1,a=a*a%mod)if(b&1)ret=ret*a%mod;return ret;}
il ll qmul(ll a,ll b,ll p){ll ret=0;for(;b;b>>=1,a=(a<<1)%p)if(b&1)adm(ret,a,p);return ret;}il ll qmul(ll a,ll b){ll ret=0;for(;b;b>>=1,a=(a<<1)%mod)if(b&1)adm(ret,a,mod);return ret;}
il void judge(){
	freopen("data.in","r",stdin);
	freopen("data.out","w",stdout);}
il void gen(){freopen("data.in","w",stdout);}
int n,x[N],y[N],tot,rt;
pa p[N];int o;
struct edge{int t,ne;}e[N];
int head[N],ec,id[N];
#define YES(a) ((a)<<1)
#define NO(a) (((a)<<1)|1)
#define REV(a) ((a)^1)
#define mid ((l+r)>>1)
void adde(int a,int b){
	//printf("%d %d\n",a,b);
	e[++ec]=(edge){b,head[a]};head[a]=ec;
	a=REV(a);b=REV(b);swap(a,b);
	e[++ec]=(edge){b,head[a]};head[a]=ec;
}
int dfn[N],low[N],st[N],inst[N],bel[N],top,scc,dex;
void tarjan(int x){
	dfn[x]=low[x]=++dex;st[++top]=x;inst[x]=1;
	run(x)if(!dfn[v])tarjan(v),gmin(low[x],low[v]);else
		if(inst[v])gmin(low[x],dfn[v]);
	if(dfn[x]==low[x]){
		scc++;
		while(st[top]!=x)bel[st[top]]=scc,inst[st[top--]]=0;
		bel[x]=scc;inst[x]=0;top--;
	}
}
int ls[N],rs[N];
void gao(int k,int l,int r,int x,int y,int id){
	if(l==x&&r==y){if(l!=r)adde(id,YES(k));else adde(id,k);return;}
	if(y<=mid)gao(ls[k],l,mid,x,y,id);else
	if(x> mid)gao(rs[k],mid+1,r,x,y,id);else{
		gao(ls[k],l,mid,x,mid,id);
		gao(rs[k],mid+1,r,mid+1,y,id);
	}
}
void build(int&k,int fa,int l,int r){
	if(l==r){
		k=REV(p[l].w2);
		if(fa)adde(YES(fa),k);
		return;
	}
	k=++tot;
	if(fa)adde(YES(fa),YES(k));
	build(ls[k],k,l,mid);
	build(rs[k],k,mid+1,r);
}
bool ok(int d){
	rep(i,1,tot*2)head[i]=dfn[i]=low[i]=bel[i]=inst[i]=ls[i]=rs[i]=0;
	tot=n;ec=scc=top=dex=0;
	build(rt,0,1,n+n);
	int l=1,r=1;
	rep(i,1,n+n){
		while(p[i].w1-p[l].w1>=d)l++;
		while(r<n+n&&p[r+1].w1-p[i].w1<d)r++;
		if(l<i)gao(rt,1,n+n,l,i-1,p[i].w2);
		if(r>i)gao(rt,1,n+n,i+1,r,p[i].w2);
	}
	rep(i,2,tot*2+1)
		if(!dfn[i])tarjan(i);
	rep(i,1,n)if(bel[YES(i)]==bel[NO(i)])return 0;
	return 1;
}
int main(){
	read(n);rep(i,1,n)read(x[i],y[i]),p[++o]=pa(x[i],YES(i)),p[++o]=pa(y[i],NO(i));//no yes
	sort(p+1,p+1+o);
	int r=1e9,l=1,res=0;
	while(l<=r){
		if(ok(mid))
			res=mid,l=mid+1;
				else r=mid-1;
	}
	cout<<res<<endl;
}

Measured memory_bytes: 38656