//缓缓飘落的枫叶像思念，我点燃烛火温暖岁末的秋天。
//堆排序找top k;
#include<bits/stdc++.h>
#define IO ios::sync_with_stdio(0);cin.tie(0);
using namespace std;
typedef long long ll;
const ll N=2e6;
int a[5];
int main()
{

    cin>>a[1]>>a[2]>>a[3];
    sort(a+1,a+4);
    if(a[3]-a[2]==a[2]-a[1])cout<<"Yes";
    else
    cout<<"No";

}
  


    
    
    
    
    
    
    

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

int main() {
	cin.tie(NULL);
	ios_base::sync_with_stdio(false);

	vector<int> a(3);
	int sum = 0;
	for (int&x : a) cin >> x, sum += x;
	sort(a.begin(), a.end());
	if (sum % 3 != 0 || sum/3 != a[1]) cout << "No";
	else cout << "Yes";
	
	return 0;
}
