View Code of Problem 67

#include <stdio.h>
#include <string.h>
int main(){
	int d1,d2,x1,x2,y1,y2,x3,x4,y3,y4;
	float k1,k2,b1,b2;
	while(scanf("%d %d %d %d %d %d %d %d",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4)!=EOF){
		d1=x2-x1;
		d2=x4-x3;
		if(d1 ==0 && d2 == 0)
			if(x1!=x3) printf("NO\n");
			else printf("YES\n");
		else if(d1 ==0 || d2 == 0)
			printf("YES\n") ;			
		else {
			k1=(y2-y1)/(x2-x1);
			k2=(y4-y3)/(x4-x3);
			b1 = y1- k1*x1;
			b2 = y3 - k2*x3;
			if(k1 == k2 &&b1 != b2) printf("NO\n");
			else printf("YES\n");
		}
		
		
		
	}
		
	return 0;
}