Const
 Nmax=25;

Var
 A:Array[1..Nmax] of Real;
 n,i,k,q:Byte;
 M,P:Real;

Begin
 Repeat
  Write('n = ');
  Readln(n);
  if n>Nmax then writeln('Error! n must be <= ',Nmax);
 Until n<=Nmax;
 Writeln;
 Randomize;
 M:=0;
 P:=1;
 k:=0;
 q:=0;
 for i:=1 to n do
  begin
   A[i]:=(Random-0.5)*10;
   if ((i mod 2)=0) and (A[i]>0) then
    begin
     Inc(k);
     M:=M+A[i];
    end;
   if ((i mod 2)=1) and (A[i]<0) then
    begin
     Inc(q);
     P:=P*A[i];
    end;
  end;
 if k>0 then M:=M/k;
 Writeln('Array:');
 for i:=1 to n do write(A[i]:10:5);
 Writeln;
 Writeln;
 Writeln('Arithmetic mean:');
 if k=0 then writeln('No such elements!') else writeln(M:0:5);
 Writeln;
 Writeln('Product:');
 if q=0 then writeln('No such elements!') else writeln(P:0:5);
 Readln
End.