#define	_USE_MATH_DEFINES
#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cfloat>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <string>
#include <set>
using namespace std;
int main(){
	
	
	double x1,x2,x3,x4,y1,y2,y3,y4;
	double m1,m2;
	
	while(cin>>x1){
		cin>>y1>>x2>>y2>>x3>>y3>>x4>>y4;
		
		if((x2-x1)==0)
			m1=999999;
		else if((y2-y1)==0)
			m1=-999999;
		else
		m1=(y2-y1)/(x2-x1);
		if((x4-x3)==0)
			m2=999999;
		else if((y4-y3)==0)
			m2=-999999;
		else
		m2=(y4-y3)/(x4-x3);
		
		if(m1==999999&&m2==-999999||m1==-999999&&m2==999999||m1*m2==-1)
			cout<<"YES"<<endl;
		else
			cout<<"NO"<<endl;
	}
	

	
}