#include <stdio.h>

void getinput(char *prmpt, float *x, float *y);

main()
{
  float x1, x2, y1, y2, m;

  getinput("Input first point: ", &x1, &y1);
  getinput("Input second point: ", &x2, &y2);
  m = (y2 - y1) / (x2 - x1);
  printf("First: (%f,%f)\nSecond: (%f,%f)\n", x1, y1, x2, y2);

  return 0;
}

void getinput(char *prmpt, float *x, float *y)
{
  printf(prmpt);
  scanf("%f %f", x, y);
}