var
a : integer;
begin
read (a);
if (a mod 10 = a div 100) and (a mod 10 = a div 10 mod 10) then writeln ('yes') else writeln ('no');
end.
var
a : integer;
begin
read (a);
if (a mod 10 = a div 100) and (a mod 10 = a div 10 mod 10) then writeln ('yes') else writeln ('no');
end.