#include<bits/stdc++.h>
using namespace std;
int n, m, pp[100007][2], h[1000007], svh[1000007], to[3000007], nxt[3000007], pos[200007], cnt;
int dfn[1000007], low[1000007], col[1000007], tot, st[1000007], tp;
bool vis[1000007];
pair<int, int>p[200007];
int read()
{
	int num = 0;
	char c = getchar();
	while (c < '0' || c>'9')c = getchar();
	while (c >= '0' && c <= '9')num = num * 10 + c - '0', c = getchar();
	return num;
}
int add(int a, int b)
{
	cnt++;
	to[cnt] = b;
	nxt[cnt] = h[a];
	h[a] = cnt;
	return 0;
}
int mtree(int w, int l, int r)
{
	if (l == r)
	{
		add(w + 20000, pp[p[l].second][pp[p[l].second][0] == l]);
		return 0;
	}
	int mid = (l + r) / 2;
	mtree(2 * w, l, mid);
	mtree(2 * w + 1, mid + 1, r);
	add(w + 20000, 2 * w + 20000);
	add(w + 20000, 2 * w + 20001);
	return 0;
}
int tadd(int w, int l, int r, int x, int y, int v)
{
	if (x <= l && r <= y)
	{
		add(v, w + 20000);
		return 0;
	}
	int mid = (l + r) / 2;
	if (x <= mid)tadd(2 * w, l, mid, x, y, v);
	if (y > mid)tadd(2 * w + 1, mid + 1, r, x, y, v);
	return 0;
}
int dfs(int w)
{
	dfn[w] = low[w] = ++tot;
	st[++tp] = w;
	vis[w] = 1;
	for (int i = h[w]; i; i = nxt[i])
		if (!dfn[to[i]])
			dfs(to[i]), low[w] = min(low[w], low[to[i]]);
		else if(vis[to[i]])low[w] = min(low[w], dfn[to[i]]);
	if (low[w] == dfn[w])
	{
		while (st[tp] != w)
		{
			vis[st[tp]] = 0;
			col[st[tp]] = w;
			tp--;
		}
		vis[w] = 0;
		col[w] = w;
		tp--;
	}
	return 0;
}
int check(int mid)
{
	int sv = cnt;
	memcpy(h, svh, sizeof h);
	for (int i = 1; i <= m; i++)
	{
		int l = upper_bound(pos + 1, pos + m + 1, p[i].first - mid) - pos;
		int r = lower_bound(pos + 1, pos + m + 1, p[i].first + mid) - pos - 1;
		if (l != i)tadd(1, 1, m, l, i - 1, i);
		if (r != i)tadd(1, 1, m, i + 1, r, i);
	}
	memset(dfn, 0, sizeof dfn);
	memset(low, 0, sizeof low);
	for (int i = 1; i <= 100000; i++)
		if (!dfn[i])
			dfs(i);
	cnt = sv;
	for (int i = 1; i <= n; i++)
		if (col[pp[i][0]] == col[pp[i][1]])
			return 0;
	return 1;
}
int main()
{
	n = read();
	for (int i = 1; i <= n; i++)
	{
		p[++m].first = read();
		p[++m].first = read();
		p[m - 1].second = p[m].second = i;
	}
	sort(p + 1, p + m + 1);
	for (int i = 1; i <= m; i++)
		if (pp[p[i].second][0])
			pp[p[i].second][1] = i;
		else pp[p[i].second][0] = i;
	mtree(1, 1, m);
	memcpy(svh, h, sizeof svh);
	for (int i = 1; i <= m; i++)
		pos[i] = p[i].first;
	int l = 0, r = 1e9;
	while (l != r)
	{
		int mid = (l + r + 1) / 2;
		if (check(mid))l = mid;
		else r = mid - 1;
	}
	cout << l << endl;
	return 0;
}