Scanf is not taking input.I am using the following code and scanf is not taking input . I am taking double as scanf input : this is the code i am running    

    #include <stdio.h>
    #include <math.h>
  
    void main()    
    {
     int i=0;
     double kl,x0,x1,xk;
     printf("enter kl");
     scanf("%lf",&kl);  
     printf("hello");
     for(x1=kl;((x1-x0)>2) || ((x1-x0)<-2);x0 );  
      {
       x0=x1;
       x1=(x0/2.0)+(kl/(2.0*x0));
    
       }
     printf("%lf",x1); 
     printf(" %lf ",(sqrt(kl)-x1));
    } 

after running scanf is not taking input. hello is not printed.