#include <iostream>
using namespace std;

int main() {
	
	int a;
	int b;
	int c;
	
	cin >> a;
	cin >> b;
	cin >> c;
	
	if (a + b > c && a + c > b && b + c > a) {
		cout << "YES";
	} else {
		cout << "NO";
	}
	
	return 0;
}