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

/**************************************************************
	Problem: 1045
	User: zhengzihao3
	Language: C++
	Result: Wrong Answer
****************************************************************/