How to make the programme work??

/* This is "lifter.c", written to accompany Introduction to
   Scientific Programming.*/

/* This program solves the kinematics of a weightlifting robot
    */


#include <stdio.h>
#include <math.h>



main ( )
{

  int shin,           /* The lengths of the shin, thigh, and */
      thigh,          /* torso in millimeters. m is to end programme */
      torso,
      m ; 

  double kneeX,       /* The x-y coordinates of the knee and hip, and */
         kneeY,       /* the y-coordinate of the shoulder.  The origin */
         hipX,        /* of the coordinate system is at the ankle, and */
         hipY,        /* the x-coordinate of the shoulder is */
         shoulderY;   /* constrained to be zero. */

  double ankleAngle,  /* The angles in degrees formed by ground and */
         kneeAngle,   /* shin (ankle), shin and thigh (knee), and thigh */
         hipAngle;    /* and torso (hip). */
  
  double alpha,       /* The measurements in radians of the angles from */
         beta,        /* Figure 11.2 of the text. */
         gamma;

  double pi;          /* The value of pi. */


  /* We begin by prompting for "kneeAngle" and "torso". */
  
  printf("Enter knee angle (deg): ");
  scanf("%lf", &kneeAngle);

  printf("Enter torso length (mm): ");
  scanf("%d", &torso);


  /* We calculate pi using arccos.  This works because cos(pi) = -1. */

  pi = acos (-1);


  /* We assumed these relationships when developing the model in
     Chapter 11. */

  ankleAngle = kneeAngle / 2;
  thigh = 0.67 * torso;
  shin = 0.59 * torso;


  /* We calculate "alpha" and the knee coordinates ... */

  alpha = (ankleAngle / 180) * pi;
  kneeX = shin * cos(alpha);
  kneeY = shin * sin(alpha);

  /* ... "beta" and the hip coordinates ... */

  beta = (kneeAngle / 180) * pi - alpha;
  hipX = kneeX - thigh * cos(beta);
  hipY = kneeY + thigh * sin(beta);

  /* ... and "gamma", "hipAngle", and the shoulder coordinate. */

  gamma = acos(-hipX/torso);
  hipAngle = ((gamma + beta) / pi) * 180;
  shoulderY = hipY + torso * sin(gamma);


  /* Finally, we display our results. */

  printf("\nTorso = %d mm\n", torso);
  printf("Thigh = %d mm\n", thigh);
  printf("Shin  = %d mm\n", shin);
  
  printf(" pi = %g \n", pi);
  
  printf("\nAnkle angle = %g deg\n", ankleAngle);
  printf("          X = %g mm\n", 0.0);
  printf("          Y = %g mm\n", 0.0);

  printf("\nKnee angle = %g deg\n", kneeAngle);
  printf("         X = %g mm\n", kneeX);
  printf("         Y = %g mm\n", kneeY);

  printf("\nHip angle = %g deg\n", hipAngle);
  printf("        X = %g mm\n", hipX);
  printf("        Y = %g mm\n", hipY);

  printf("\nShoulder X = %g mm\n", 0.0);
  printf("         Y = %g mm\n\n\n\n", shoulderY);

  printf("press x to exit :");
  scanf("%d", m);

}