uses crt;
var
a:array[1..100]of integer;
i,p,p0,p1,sum,temp,n,j:integer;
begin clrscr;
write('n=');
read(n);
for i:=1 to n do
 begin
  write('a[',i,']=');
  read(a[i]);
 end;
writeln;
p:=1;
for i:=1 to n do
if i mod 2=0 then p:=p*a[i];
writeln('proizvedenie=',p);
writeln;
for i:=n downto 1 do
if a[i]=0 then p0:=i;
writeln('pervyi 0 v pozicii - ',p0);
writeln;
for i:=1 to n do
if a[i]=0 then p1:=i;
writeln('poslednii 0 v posicii - ',p1);
writeln;
sum:=0;
for i:=p0 to p1 do
sum:=sum+a[i];
writeln('summa=',sum);
writeln;
readkey;
end.