#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;
}