#include<bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)n;i++)
#define all(c) (c).begin(),(c).end()
#define pb push_back
#define dbg(...) do{cerr<<__LINE__<<": ";dbgprint(#__VA_ARGS__, __VA_ARGS__);}while(0);

using namespace std;

namespace std{template<class S,class T>struct hash<pair<S,T>>{size_t operator()(const pair<S,T>&p)const{return ((size_t)1e9+7)*hash<S>()(p.first)+hash<T>()(p.second);}};template<class T>struct hash<vector<T>>{size_t operator()(const vector<T> &v)const{size_t h=0;for(auto i : v)h=h*((size_t)1e9+7)+hash<T>()(i)+1;return h;}};}
template<class T>ostream& operator<<(ostream &os, const vector<T> &v){os<<"[ ";rep(i,v.size())os<<v[i]<<(i==v.size()-1?" ]":", ");return os;}template<class T>ostream& operator<<(ostream &os,const set<T> &v){os<<"{ "; for(const auto &i:v)os<<i<<", ";return os<<"}";}
template<class T,class U>ostream& operator<<(ostream &os,const map<T,U> &v){os<<"{";for(const auto &i:v)os<<" "<<i.first<<": "<<i.second<<",";return os<<"}";}template<class T,class U>ostream& operator<<(ostream &os,const pair<T,U> &p){return os<<"("<<p.first<<", "<<p.second<<")";}
void dbgprint(const string &fmt){cerr<<endl;}template<class H,class... T>void dbgprint(const string &fmt,const H &h,const T&... r){cerr<<fmt.substr(0,fmt.find(","))<<"= "<<h<<" ";dbgprint(fmt.substr(fmt.find(",")+1),r...);}
typedef long long ll;typedef vector<int> vi;typedef pair<int,int> pi;const int inf = (int)1e9;const double INF = 1e12, EPS = 1e-9;

int N;
vector<vi> e;

void rec(int from, int a, int b, int k, int l, int r){
	if(b <= a || b <= l || a >= r) return;
	if(a <= l && r <= b){
		//dbg(from, k);
		e[from].pb(k);
		return;
	}
	rec(from, a, b, 2 * k + 1, l, (l + r) / 2);
	rec(from, a, b, 2 * k + 2, (l + r) / 2, r);
}

void visit(const vector<vi> &g, int v, vector< vector<int> >& scc,
    stack<int> &S, vector<bool> &inS,
    vector<int> &low, vector<int> &num, int& time) {
  low[v] = num[v] = ++time;
  S.push(v); inS[v] = true;
  for(int e: g[v]) {
    int w = e;
    if (num[w] == 0) {
      visit(g, w, scc, S, inS, low, num, time);
      low[v] = min(low[v], low[w]);
    } else if (inS[w])
      low[v] = min(low[v], num[w]);
  }
  if (low[v] == num[v]) {
    scc.push_back(vector<int>());
    while (1) {
      int w = S.top(); S.pop(); inS[w] = false;
      scc.back().push_back(w);
      if (v == w) break;
    }
  }
}
void stronglyConnectedComponents(const vector<vi>& g,
    vector< vector<int> >& scc) {
  const int n = g.size();
  vector<int> num(n), low(n);
  stack<int> S;
  vector<bool> inS(n);
  int time = 0;
  rep(u, n) if (num[u] == 0)
    visit(g, u, scc, S, inS, low, num, time);
}

int main(){
	cin.tie(0); cin.sync_with_stdio(0);
	int n; cin >> n;
	vector<pi> v;
	rep(i, n){
		int x, y; cin >> x >> y;
		v.emplace_back(x, i);
		v.emplace_back(y, i + n);
	}
	sort(all(v));
	vi pos(2 * n);
	rep(i, 2 * n) pos[v[i].second] = i;
	rep(i, n) swap(pos[i], pos[i + n]);
	
	//rep(i, 2 * n) dbg(i, v[i]); rep(i, 2 * n) dbg(i, pos[i]);
	
	for(N = 1; N < 2 * n; N *= 2);
	int lo = 0, hi = inf, mid;
	while(lo + 1 < hi){
		mid = (lo + hi) / 2;
		
		e.clear();
		e.resize(2 * N - 1);
		
		for(int i = N - 2; i >= 0; i--){
			e[i].pb(i * 2 + 1);
			e[i].pb(i * 2 + 2);
		}
		rep(i, 2 * n){
			int p = pos[v[i].second];
			int l = v[p].first - mid, r = v[p].first + mid;
			
			//dbg(i, v[i], l, r);
			
			l = lower_bound(all(v), pi(l, inf)) - v.begin();
			r = lower_bound(all(v), pi(r, 0)) - v.begin();
			
			//dbg(i, v[i], l, r);
			
			rec(i + N - 1, l, p, 0, 0, N);
			rec(i + N - 1, p + 1, r, 0, 0, N);
		}
		
		vi to(N);
		vector<vi> scc;
		stronglyConnectedComponents(e, scc);
		
		rep(i, scc.size()) for(int j : scc[i]) if(j >= N - 1) to[j - N + 1] = i;
		rep(i, 2 * n) if(to[i] == to[pos[v[i].second]]){
			hi = mid;
			goto NEXT;
		}
		lo = mid;
		NEXT:;
		
		//dbg(scc); dbg(to);
	}
	cout << lo << endl;
	return 0;
}

Measured memory_bytes: 14600