View Code of Problem 67

#include<stdio.h>
int 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(x1==x3)
			printf("Yes\n");
			else 
			printf("No\n");
		}
		else{
			k1=(y1-y2)/(x1-x2);
			k2=(y3-y4)/(x3-x4);
			if(k1!=k2){
				printf("Yes\n");
			}
			else{
				if(k1*(x3-x2)+y2==y3){
					printf("Yes\n");
				}
				else{
					printf("No\n");
				}
			}
		}
		
	}
	return 0;
}