#include <iostream>

using namespace std;

int main(void) {
  double x1, y1;  //first point
  double x2, y2;  //second point
  double m;       //slope (Dr. Milford)
  double b;       //y-intercept
  
  //get two points
  cout << "Enter x1: ";
  cin >> x1;
  cout << "Enter y1: ";
  cin >> y1;
  cout << "Enter x2: ";
  cin >> x2;
  cout << "Enter y2: ";
  cin >> y2;
  
  //find the slope
  m = (y2-y1)/(x2-x1);
  
  //find the y intercept
  b=y1 - m*x1;

  //display the result
  if(b < 0) {
    //negative y-intercept
    cout << "Y=" << m << "x - " << -b << endl;
  } else {
    //positive y-intercept
    cout << "Y=" << m << "x + " << b << endl;
  }
  return 0;
}