#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <sstream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <numeric>
#include <cctype>
#include <tuple>
#include <array>
#include <climits>
#include <bitset>
#include <cassert>
#include <unordered_map>
#include <complex>

#ifdef _MSC_VER
#include <agents.h>
#endif

#define FOR(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep(i, n) FOR(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define REV(v) v.rbegin(), v.rend()
#define MEMSET(v, s) memset(v, s, sizeof(v))
#define UNIQUE(v) (v).erase(unique(ALL(v)), (v).end())
#define MP make_pair
#define MT make_tuple

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;

const int N = 1010;
int par[N];

int find(int x){
	if (x == par[x]) return x;
	return par[x] = find(par[x]);
}

void unite(int x, int y){
	par[find(x)] = find(y);
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout.setf(ios::fixed);
	cout.precision(20);

	int n;
	cin >> n;
	vector<ll> x(n), y(n);
	rep(i, n) cin >> x[i] >> y[i];

	vector<tuple<ll, int, int>> edge;
	rep(i, n) rep(j, i){
		ld dist = sqrt((x[i] - x[j])*(x[i] - x[j]) + (y[i] - y[j])*(y[i] - y[j]));
		ll x = dist;
		if (x < dist) ++x;
		while (x % 10) ++x;
		edge.push_back(MT(x, i, j));
	}

	rep(i, n) par[i] = i;

	sort(ALL(edge));
	ll ans = 0;
	int cnt = 1;
	for (auto e : edge){
		ll cost;
		int x, y;
		tie(cost, x, y) = e;
		if (find(x) == find(y)) continue;
		unite(x, y);
		++cnt;
		ans = max(ans, cost);
		if (find(0) == find(n - 1)) break;
	}
	cout << ans << endl;
}