int main()//?????
{
	int n,i,j;//??????n,i,j
	float distance=0;//??????distance????0
	float x[1024],y[1024],d[1024][1024],dis[1024][1024];//???????????????????
	cin>>n;//????n
	for(i=0;i<n;i++)
	{
		cin>>x[i]>>y[i];
	}//??????
	for(i=0;i<n;i++)
		for(j=0;j<n;j++)
		{
			d[i][j]=(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]);
			dis[i][j]=sqrt(d[i][j]);
		}//???????????
		for(i=0;i<n;i++)
		    for(j=0;j<n;j++)
			{
				if (distance<dis[i][j])
				{
					distance=dis[i][j];
				}
			}//??????
			printf("%.4f\n",distance);//??????4????????distance
			return 0;
}//?????
