#include<cstdio>
using namespace std;

int main(){
	double x[4], y[4];
	while(1){
		for( int i=0; i<4; i++ )
			if( scanf("%lf %lf", &x[i], &y[i])!=2 )	break;
		double v1[2] = {x[1]-x[0], y[1]-y[0]},
			   v2[2] = {x[3]-x[2], y[3]-y[2]};
		if( v1[0]*v2[0]+v1[1]*v2[1] == 0.0 )
			printf("YES\n");
		else
			printf("NO\n");
	}
	return 0;
}