#include<iostream>

using namespace std;

struct straight{
	double xA,yA,xB,yB;
};

int main(void){
	struct straight str[2];
	while(cin>>str[0].xA>>str[0].yA>>str[0].xB>>str[0].yB
		  	 >>str[1].xA>>str[1].yA>>str[1].xB>>str[1].yB){
		
		double temp,tline[4];
		
		tline[0]=str[0].yA-str[0].yB;
		tline[1]=str[1].yA-str[1].yB;
		tline[2]=str[0].xA-str[0].xB;
		tline[3]=str[1].xA-str[1].xB;
		
		temp=(tline[0]*tline[1])/(tline[2]*tline[3]);
		
		if(tline[0]==0 && tline[3]==0 || tline[1]==0 && tline[2]==0 || temp==-1){
			cout<<"YES"<<endl;
		}
		else{
			cout<<"NO"<<endl;
		}
	}
}