program z16_37;
var x,y:integer;
f:boolean;
BEGIN
write('vvedite chislo');
readln(x);
if x=0 then writeln('pusto')
else begin
f:=true;
write('vvedite chislo');
readln(y);
while y<>0 do begin
if x*y>0 then f:=false;
x:=y;
write('vvedite chislo');
readln(y);
end;
if f then writeln('znakochereduetsa')
else writeln(' ne znakochereduetsa');
readln;
end;
END.