#include"bits/stdc++.h"


#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fr(x) freopen(x,"r",stdin)
#define fw(x) freopen(x,"w",stdout)
#define iout(x) printf("%d\n",x)
#define lout(x) printf("%lld\n",x)
#define REP(x,l,u) for(int x = (l);x<=(u);x++)
#define RREP(x,l,u) for(int x = (l);x>=(u);x--)
#define mst(x,a) memset(x,a,sizeof(x))
#define PII pair<int,int>
#define PLL pair<ll,ll>
#define MP make_pair
#define se second
#define fi first
#define dbg(x) cout<<#x<<" = "<<(x)<<endl;
#define sz(x) ((int)x.size())
#define cl(x) x.clear()

typedef  long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
using namespace std;

const int maxn = 200010;
const int mod = 1e9+7;
const int MAX = 1000000010;
const double eps = 1e-6;
const double PI = acos(-1);

template<typename T> inline void read(T &x){
x=0;T f=1;char ch;do{ch=getchar();if(ch=='-')f=-1;}while(ch<'0'||ch>'9');do x=x*10+ch-'0',ch=getchar();while(ch<='9'&&ch>='0');x*=f;
}

template<typename A,typename B> inline void read(A&x,B&y){read(x);read(y);}
template<typename A,typename B,typename C> inline void read(A&x,B&y,C&z){read(x);read(y);read(z);}
template<typename A,typename B,typename C,typename D> inline void read(A&x,B&y,C&z,D&w){read(x);read(y);read(z);read(w);}
template<typename A,typename B> inline A fexp(A x,B p){A ans=1;for(;p;p>>=1,x=1LL*x*x%mod)if(p&1)ans=1LL*ans*x%mod;return ans;}
template<typename A,typename B> inline A fexp(A x,B p,A mo){A ans=1;for(;p;p>>=1,x=1LL*x*x%mo)if(p&1)ans=1LL*ans*x%mo;return ans;}

int n,N;

PII A[maxn];

vector<int> G[maxn],G2[maxn];

int vi[maxn],S[maxn],scc[maxn],scccnt,top;

struct Node{
	int l,r;
}T[maxn];

int OP(int x){
	int nn=n>>1;
	if(x<=nn)return x+nn;
	else return x-nn;
}

void build(int i,int l,int r){
	T[i].l=l;T[i].r=r;G[i+n].clear();N=max(N,i+n);
	if(l==r){
		G[i+n].PB(OP(A[l].se));
		return;
	}
	int M=l+r>>1;
	build(i<<1,l,M);build(i<<1|1,M+1,r);
	G[i+n].PB((i<<1)+n);G[i+n].PB((i<<1|1)+n);
}

void add(int i,int l,int r,int s){
	if(l<=T[i].l&&T[i].r<=r){
		G[s].PB(i+n);
		return;
	}
	int M=T[i].l+T[i].r>>1;
	if(l<=M)add(i<<1,l,r,s);if(r>M)add(i<<1|1,l,r,s);
}

void dfs(int u){
	if(vi[u])return;vi[u]=1;
	for(auto v:G[u])dfs(v);
	S[++top]=u;
}
void dfs2(int u){
	if(scc[u])return;scc[u]=scccnt;
	for(auto v:G2[u])dfs2(v);
}

void findscc(){
	REP(i,1,N)G2[i].clear();
	REP(u,1,N)for(auto v:G[u])G2[v].PB(u);
	REP(i,1,N)vi[i]=scc[i]=0;
	top=0;
	REP(i,1,N)dfs(i);
	scccnt=0;
	RREP(i,N,1){
		int x=S[i];
		if(!scc[x]){
			scccnt++;
			dfs2(x);
		}
	}
}

bool check(int M){
	REP(i,1,n)G[i].clear();
	N=0;build(1,1,n);
	REP(i,1,n){
		int x=LB(A+1,A+n+1,MP(A[i].fi-M+1,0))-A;
		if(x<i)add(1,x,i-1,A[i].se);
		x=UB(A+1,A+n+1,MP(A[i].fi+M-1,n+1))-A-1;
		if(x>i)add(1,i+1,x,A[i].se);
	}
//	cout<<N<<endl;
	findscc();
//	REP(i,1,N)cout<<scc[i]<<' ';cout<<endl;
	int nn=n>>1;
	REP(i,1,nn)if(scc[i]==scc[i+nn])return false;
	return true;
}

void Work(){
	int l=0,r=A[n].fi-A[1].fi;
	while(l<r){
		int M=(l+r>>1)+1;
		if(check(M))l=M;else r=M-1;
	}
	iout(l);
}

void Init(){
	read(n);
	REP(i,1,n){
		read(A[i].fi),A[i].se=i;
		read(A[i+n].fi),A[i+n].se=i+n;
	}
	n<<=1;
	sort(A+1,A+n+1);
}

int main(){
	Init();
	Work();
	return 0;
}


Measured memory_bytes: 29440