#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define pb push_back
#define li long int
#define fi first
#define se second
#define ve vector<ll>
#define mp make_pair
#define pr pair<ll,ll>
#define rep(i,n) for(ll i=0;i<n;i++)
#define repji(j,i,n) for(ll j=i;j<n;j++)
#define rev(i,n) for(ll i=n;i>=0;i--)
#define speed ios_base::sync_with_stdio(false);cin.tie(NULL)
int main()
{
speed;
ll a[3];
cin>>a[0]>>a[1]>>a[2];
sort(a,a+3);
if(a[1]-a[0]==a[2]-a[1])
cout<<"Yes";
else
cout<<"No";

return 0;
}
#include<iostream>
using namespace std;

int main()
{
	int a1, a2, a3;
	cin >> a1 >> a2 >> a3;
	int aa = a1;
	if (a2 > aa)aa = a2;
	if (a3 > aa)aa = a3;
	int ss = a1;
	if (a2 < ss)ss = a2;
	if (a3 < ss)ss = a3;
	int dd = a1 + a2 + a3 - aa - ss;
	if (aa - dd == dd - ss)cout << "Yes";
	else cout << "No";
	return 0;
}