#include<bits/stdc++.h>
using namespace std;
int main(){
	int a,b,c;
	cin>>a>>b>>c;
	if(a+b>c){
		if(a+c>b){
			if(b+c>a){
				cout<<"yes";
			}
		}
	}else{
		cout<<"no";
	}
}
/**************************************************************
	Problem: 1045
	User: wangyiyang
	Language: C++
	Result: Wrong Answer
****************************************************************/