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

	return 0;
}

/**************************************************************
	Problem: 1045
	User: wqc123
	Language: C++
	Result: Wrong Answer
****************************************************************/