View Code of Problem 67

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


return 0;
}