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


    return 0;
}

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