#include<bits/stdc++.h>
#define FASTIO ios_base::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL);
#define mod 1000000007
#define INF 10000000000000001
#define F first
#define S second
#define LB lower_bound
#define UB upper_bound
#define vc vector
#define vll vector<long long>
#define pll pair<long long,long long>
#define pb push_back
#define all(v) v.begin(),v.end()
#define T ll test;cin>>test; while(test--)
#define forn(i,a,n) for(ll i=a;i<(long long)n;++i)
#define backn(i,n,a) for(ll i=n;i>(long long)a;--i)
#define MAX 200005
#define sz(x) (ll)x.size()
#define ins insert
#define mp make_pair
#define lld long long int
#define cy cout<<"Yes\n";
#define cno cout<<"No\n";
typedef  long long ll;
typedef long double ld;
using namespace std;

signed main()
{
  	FASTIO
  	int a,b,c;
  	cin >> a >> b >> c;
  	int x=2*a;
  	int y=2*b;
  	int z=2*c;
  	if(x==b+c)
  	{
  		cout << "Yes"<< endl;
  		return 0;
	}
	else if(y==a+c)
  	{
  		cout << "Yes"<< endl;
  		return 0;
	}
	else if(z==a+b)
  	{
  		cout << "Yes"<< endl;
  		return 0;
	}
	else
	{
		cout << "No" << endl;
	}
}

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
constexpr ll MOD = 1e9 + 7;
//constexpr ll MOD = 998244353;
//constexpr ll MOD = ;
ll mod(ll A, ll M) {return (A % M + M) % M;}
constexpr ll INF = 1LL << 60;
template<class T> bool chmin(T& a, T b) {if (a > b) {a = b; return true;} return false;}
template<class T> bool chmax(T& a, T b) {if (a < b) {a = b; return true;} return false;}
ll divceil(ll A, ll B) {return (A + (B - 1)) / B;}
#define FINALANS(A) do {cout << (A) << '\n'; exit(0);} while (false)

int main()
{
  ll N = 3;
  vector<ll> A(N);
  for (ll i = 0; i < N; i++)
  {
    cin >> A.at(i);
  }
  sort(A.begin(), A.end());

  cout << ((A.at(2) - A.at(1) == A.at(1) - A.at(0)) ? "Yes" : "No") << endl;
}