#include<iostream>
using namespace std;
 
double x[4], y[4];

int main()
{
    while( 1 ){
        for( int i = 0; i < 4; i++ ){
            if( !( cin >> x[i] >> y[i] ) ) return 0;
        }
     
        if( ( x[1] - x[0] ) * ( x[3] - x[2] ) + ( y[1] - y[0] ) * ( y[3] - y[2] ) == 0 ){
            cout << "YES\n";
        }
        else{
            cout << "NO\n";
        }
    }
 
    return 0;
}