View Code of Problem 67

#include <stdio.h>

void main()
{
	float x1,x2,x3,x4,y1,y2,y3,y4;
	while(scanf("%f%f%f%f",&x1,&y1,&x2,&y2) != EOF)
	{
		scanf("%f%f%f%f",&x3,&y3,&x4,&y4);
		float k1,k2;
		if(x1==x2 && x3==x4)
		{
			if(x2==x3)
			{
				printf("Yes\n");
			}else
			{
				printf("No\n");
			}
		}else
		{
			k1=(y2-y1)/(x2-x1);
			k2=(y4-y3)/(x4-x3);
			if(k1 !=k2)
			{
				printf("Yes\n");
			}else
			{
				if(k1*(x3-x1)+y1==y3)
				{
					printf("Yes\n");
				}else
				{
					printf("No\n");
				}
			}
		}
	}
}