#include <bits/stdc++.h>
#include <array>
#include <cstdlib>
using namespace std;

int main() {
  vector<int> a(3);
  for(int i =0; i < 3; i++){
    cin >> a[i];
  }
  sort(a.begin(), a.end());
  if(a[2]-a[1] == a[1]-a[0]){
    cout << "Yes" << endl;
  }
  else cout << "No" << endl;





}

#include<stdio.h>
#include<iostream>
#include<string.h>
using namespace std;
int main()
{
    int v,t,s,d;
    cin>>v>>t>>s>>d;
    if(v*t<=d&&s*v>=d)
    {
        cout<<"No";
    }
    else cout<<"Yes";
}