#include <bits/stdc++.h>
#define rep(i,j,k) for(int i=(int)j;i<(int)k;i++)
#define rrep()
#define Sort(x) sort((x).begin(),(x).end())
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define vi vector<int>
#define INF (int)1e9
#define INFL 1e18
#define MOD 1000000007
#define pb push_back
#define MP make_pair
typedef long long int ll;
typedef std::pair<int,int> P;
int D=1;
int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

using namespace std;

int main(){
    double x[4],y[4];
    while(cin>>x[0]>>y[0]){
    rep(i,1,4)cin>>x[i]>>y[i];
    
    if(((y[1]-y[0])/(x[1]-x[0]))*((y[3]-y[2])/(x[3]-x[2]))==-1)cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
    }
    return 0;
}

