Var a,i,x1,x2,S:integer;
begin
S:=0;
x1:=0;
a:=1;
While (a<>0) do
begin
Writeln('Vvodite elementi stroki , po okonchanii vvedi 0 ') ;
readln(a);
x2:=x1;
x1:=a;
if (x2=x1) then
S:=1;
end;
if (S=1) then
Writeln('sushestvyet')
else
Writeln('ne sushestvyet');
end.