#include <iostream>
int main() {
	int p, q, r;
	std::cin >> p >> q >> r;
    const int s = p + r;
    if(s & 1) {
        std::cout << "No\n";
        return 0;
    }
	std::cout << (s / 2 == q ? "Yes\n" : "No\n");
}