#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
const int MAX_N = 1010;
struct UnionFind{
    int par[MAX_N];
    void init(int n){
        for(int i = 0;i < n;i++)par[i] = i;
    }
    int root(int x){
        if(par[x] == x)return x;
        else return par[x] = root(par[x]);
    }
    bool same(int x,int y){
        return root(x) == root(y);
    }
    void unite(int x,int y){
        x = root(x);
        y = root(y);
        if(x == y)return;
        par[y] = x;
    }
};
main(){
    int N;
    cin >> N;
    vector<int>X(N),Y(N);
    rep(i,0,N)cin >> X[i] >> Y[i];
    UnionFind uf;
    uf.init(N);
    rep(i,0,N)rep(j,0,N){
        ll dif = (X[i] - X[j]) * (X[i] - X[j]) + (Y[i] - Y[j]) * (Y[i] - Y[j]);
        if(dif > 100)continue;
        uf.unite(i,j);
    }
    int maxi = 0;
    rep(i,0,N)rep(j,0,N){
        if(!uf.same(i,j))continue;
        maxi = max(maxi, (X[i] - X[j]) * (X[i] - X[j]) + (Y[i] - Y[j]) * (Y[i] - Y[j]));
    }
    printf("%.9lf\n",N != 0 ? sqrt(maxi) + 2 : 1);

}