Var a,b,n,i:integer;
begin
read (n);
b:=0;
For i:=1 to n do begin
read (a);
b:=b+a*2;
end;
Writeln (b);
end.
Var a,b,n,i:integer;
begin
read (n);
b:=0;
For i:=1 to n do begin
read (a);
b:=b+a*2;
end;
Writeln (b);
end.