program discount;
uses wincrt;
var
a,b,c:integer;
begin
writeln ('a=');
read(a);
writeln ('b=');
read(b);
writeln ('c=');
read(c);
        if (a+b>c)and(a+c>b)and(b+c>a) then
            begin
                writeln ('yes');
                end
        else

         writeln ('no');
        
readln
end.