//************************//
//*? ? ??????.cpp*//
//*?    ?????      *//
//*??????????  *//
//************************//
int main()                                 //???
{
    int n;                                 //???????????n
    cin>>n;                                //?????n
    double x[100],y[100];                  //???????????x???y??
    double dis=0.0000,distemp=0.0000;      //??????????dis?distemp
    int i=0,j=0;
    for (i=0;i<n;i++)
    {
        cin>>x[i]>>y[i];                   //???????????????
        if(i>0)
       {
	   for(j=0;j<i;j++)
           {
	      distemp=sqrt((x[j]-x[i])*(x[j]-x[i])+(y[j]-y[i])*(y[j]-y[i]));//?????????????????????
	      if (distemp>dis)          //??distemp>dis
	      dis=distemp;              //?distemp????dis
	   }
        }
     }
    printf("%.4f\n", dis);                //??dis??????????4?
    return 0;
}