%:pragma GCC optimize(2)
#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <vector>
using namespace std;

const int N = 10005 * 10;
const int M = N * 85;

int fir[N] , ne[M], to[M] , cnt = 1 , block[N] , n  , x[N] , y[N] , tot , Size , whe[N] , mi[N] , mx[N];
int dfn[N] , low[N] , scc_no[N] , stk[N] , top, dfs_clock , col , du , Lc[N] , Rc[N] , L[N] , R[N] , rt , all;

struct NODE {
	int id , wh , val;
	friend bool operator < (NODE xxx , NODE yyy) {
		return xxx.val < yyy.val;
	}
}P[N];

#define lc(x) (x << 1)
#define rc(x) (x << 1 | 1)

void add(int x , int y) {
	ne[++ cnt] = fir[x]; fir[x] = cnt; to[cnt] = y;
}

void link(int x , int y) {
	add(x , y); add(y ^ 1 ,  x ^ 1);
}

int abs(int x) {
	return (x < 0) ? - x : x;
}

int build(int l , int r) {
	L[++ all] = l; R[all] = r;
	if(l == r) {
		link(lc(all) , P[l].id ^ 1);
		return all;
	}
	int cur = all;
	int mid = (l + r) >> 1;
	Lc[cur] = build(l , mid);
	Rc[cur] = build(mid + 1 , r);
	link(lc(cur) , lc(Lc[cur]));
	link(lc(cur) , lc(Rc[cur]));
	return cur;
}

void addtag(int no , int wh , int l , int r) {
	if(L[no] == l && R[no] == r) {
		link(wh , lc(no)); return;
	}
	int mid = (L[no] + R[no]) >> 1;
	if(l > mid) addtag(Rc[no] , wh , l , r);
	else if(r <= mid) addtag(Lc[no] , wh , l , r);
	else {
		addtag(Lc[no] , wh , l , mid); addtag(Rc[no] , wh , mid + 1 , r);
	}
}

void Build(int cur) {
	memset(fir , 0 , sizeof(fir));
	cnt = 0; tot = du;
	all = n;
	rt = build(1 , du);
	int l = 1 , r = 1;
	for(int i = 1;i <= du;i ++) {
		while(abs(P[l].val - P[i].val) >= cur && l < i) l ++;
		while(r < du && abs(P[r + 1].val - P[i].val) < cur) r ++;
		if(l <= i - 1)
		addtag(rt , P[i].id , l , i - 1);
		if(i + 1 <= r)
		addtag(rt , P[i].id , i + 1 , r);
	}
}

#define Foreachson(i , x) for(int i = fir[x];i;i = ne[i])
bool die = 0;

void dfs(int x) {
	if(die) return;
	low[x] = dfn[x] = ++ dfs_clock; stk[++ top] = x;
	Foreachson(i , x) {
		int V = to[i];
		if(dfn[V]) {
			if(!scc_no[V])low[x] = min(low[x] , low[V]);
		}
		else {
			dfs(V); low[x] = min(low[x] , low[V]);
		}
	}
	if(low[x] == dfn[x]) {
		col ++;
		for(;;) {
			scc_no[stk[top --]] = col;
			if(scc_no[stk[top + 1]] == scc_no[stk[top + 1] ^ 1]) {
				die = 1; return;
			}
			if(stk[top + 1] == x) break;
		}
	}
}

bool SAT(void) {
	die = 0;
	memset(dfn , 0 , sizeof(dfn)); memset(low , 0 , sizeof(low)); memset(scc_no , 0 , sizeof(scc_no)); top = col = dfs_clock = 0;
	for(int i = 2;i <= rc(tot);i ++) {
		if(!dfn[i]) dfs(i);
		if(die) return 0;
	}
	for(int i = 1;i <= rc(tot);i ++) {
		if(scc_no[lc(i)] == scc_no[rc(i)]) return 0;
	}
	return 1;
}

bool pd(int x) {
	Build(x);
	return SAT();
}

int main(void) {
	int Max = 0;
//	freopen("A.in" , "r" , stdin);
//	freopen("A.out" , "w" , stdout);
	scanf("%d" , &n);
	if(n == 1) {
		puts("0");
		return 0;
	}
	for(int i = 1;i <= n;i ++) {
		scanf("%d%d" , &x[i] , &y[i]);
		P[++ tot].id = lc(i); P[tot].wh = i; P[tot].val = x[i];
		P[++ tot].id = rc(i); P[tot].wh = i; P[tot].val = y[i];
		Max = max(Max , x[i]); Max = max(Max , y[i]);
	}
	du = tot;
	sort (P + 1 , P + tot + 1);
	memset(mi , 127, sizeof(mi));
	int l = 0 , r = Max * 2 / n , ans = 0;
	while(l <= r) {
		int mid = (l + r) >> 1;
		if(pd(mid)) {
			l = mid + 1; ans = mid;
		}
		else r = mid - 1;
	}
	printf("%d\n" , ans);
}

Measured memory_bytes: 24704