#include<iostream>
#include<cstdio>
#include<cctype>
#include<string.h>
#include<math.h>
#include<cmath>
#include<algorithm>
#include<iomanip>
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;
}