#include<iostream>
using namespace std;
int main(){
	int a,b,c;
	cin>>a>>b>>c;
	if(a+b>c&&a+c>b&&c+b>c){
		cout<<"yes"<<endl;
		
	}else{
		cout<<"no"<<endl;
	}
}
/**************************************************************
	Problem: 1036
	User: admin
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/