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 %f %f %f %f", &x1, &y1, &x2, &y2, &x3, &y3, &x4, &y4)!=EOF)
	{
		float k1 = (y2 - y1) / (x2 - x1);
		float k2 = (y4 - y3) / (x4 - x3);
		float b1 = y2 - k1 * x2;
		float b2 = y4 - k2 * x4;
		if (x1 == x2 && x3 == x4)
		{
			if (x1 == x3) printf("Yes\n");
			else printf("No\n");
		}
		else
		{
			if (k1 == k2 && b1 != b2) printf("No\n");
			else printf("Yes\n");
		}
	}
}