#include<stdio.h>
#include<math.h>
#define C(a) ((a[0]-a[1])*(a[2]-a[3]))
int main()
{
	double x[4],y[4];
	for(;;)
	{
		for(int i=0;i<4;++i)if(scanf("%lf%lf",x+i,y+i)<0)return 0;
		puts(fabs(C(x)+C(y))<1e-9?"YES":"NO");
	}
}