#include<iostream>

using namespace std;

class point
{
public:
	double x,y;
	bool input()
	{
		return cin>>x>>y;
	}
};

int main(void)
{
	while(1)
	{
		point a,b,c,d;
		if(!(a.input()&&b.input()&&c.input()&&d.input()))break;
		if(a.x>b.x){
			point tmp=a;
			a=b;
			b=tmp;
		}
		if(c.x>d.x){
			point tmp=c;
			c=d;
			d=tmp;
		}
		if((b.y-a.y)*(d.y-c.y)+(b.x-a.x)*(d.x-c.x)==0)cout<<"YES"<<endl;
		else cout<<"NO"<<endl;
	}
}