#include <iostream>
using namespace std;
int main(){
int x,y,z;
cin >> x >> y >>z;
string s = "yes";
if (x + y <= z)
s = "no";
else if(x + z <= y)
s = "no";
else if(y + z <= x)
s = "no";
cout << s << endl;
return 0;
}