#include <bits/stdc++.h>
using namespace std;
int main()
{
	int a , b , c;
	cin >> a >> b >> c;
	if( a + b > c && c + b > a && c + a > b )
	{
		cout << "yes";
	}
	else
	{
		cout << "no";
	}
	return 0;
}