View Code of Problem 67

#include <stdio.h>
int main(){
  float x1,y1,x2,y2,x3,y3,x4,y4;
	 double k1,k2;
  while (scanf("%d%d%d%d%d%d%d%d",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4) != EOF){
	  if(x1==x2&&x2==x3&&x3==x4)
		  printf("Yes");
     else if((x1==x2)&&(x3==x4))
      printf("No\n");
    else if((x1==x2) ||(x3==x4))
      printf("Yes\n");
      else{
       k1=(x1-x2)/((y1-y2)*1.0);
		k2=(x3-x4)/((y3-y4)*1.0);
		if(k1 == k2){
			
			  if(y1-x1*k1==y3-x3*k2)								
					printf("Yes\n");
				else
					 printf("No\n");
 
		}
      	 
  
	  }
	  }
return 0;
}