int main(int argc,char*argv[])
{
	int i,j,n;
	double*x,*y,max=0,l;
	scanf("%d",&n);
	x=(double*)malloc(sizeof(double)*n);
	y=(double*)malloc(sizeof(double)*n);
	scanf("%lf%lf",&x[0],&y[0]);
	for(i=1;i<n;i++)
	{
		scanf("%lf%lf",&x[i],&y[i]);
	}
	for(i=1;i<n;i++)
	{
		for(j=0;j<n;j++)
		{
	
			l=sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
			if(l>max)
			{
				max=l;
			}
		}
	}
	printf("%.4lf",max);
	return 0;
}


	

