#include <stdio.h>
 
int main(void) {
    double x[4],y[4];
    int yes;
    while(1) {
        if(scanf("%lf %lf %lf %lf %lf %lf %lf %lf",
            &x[0],&y[0],&x[1],&y[1],&x[2],&y[2],&x[3],&y[3])==-1)break;
        if(x[0]==x[1]) {
            if(y[2]==y[3])yes=1; else yes=0;
        } else if(x[2]==x[3]) {
            if(y[0]==y[1])yes=1; else yes=0;
        } else {
            if(((y[0]-y[1])/(x[0]-x[1]))*((y[2]-y[3])/(x[2]-x[3]))==-1)
                yes=1;
            else yes=0;
        }
        printf("%s\n",yes?"YES":"NO");
    }
    return 0;
}