#include <stdio.h>

int main(void)
{
  float x[4],y[4];
  float ab, cd;
  int i;

  for(i=0;i<4;i++){
    scanf("%f",x+i);
    scanf("%f",y+i);
  }

  ab = cd = 999999;

  if(x[0] != x[1])
    ab = (y[0] - y[1])/(x[0] - x[1]);

  if (x[2] != x[3])
    cd = (y[2] - y[3])/(x[2] - x[3]);

  if(ab==cd)
    printf("YES\n");
  else
    printf("NO\n");

  return 0;
}