#include <iostream>
using namespace std;

int main() {
    int a, b, c;
    
    cout << "Input 3 numbers:" << endl;
    
    cin >> a >> b >> c;
    
    if (    (b - a == c - b) || // a, b, c
            (c - a == b - c) || // a, c, b
            (a - b == c - a) || // b, a, c
            (c - b == a - c) || // b, c, a
            (a - c == b - a) || // c, a, b
            (b - c == a - c)) { // c, b, a
        cout << "Yes" << endl;
    } else {
        cout << "No" << endl;
    }
    return 0;
}