#include<iostream>

double x[4], y[4];

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

 	return 0;
}