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

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