program noname;
uses crt;
var
a:array[1..1000] of integer;
i,k:integer;
s:real;
begin
clrscr;
i:=1;
k:=0;
write('vvedi chislo '); readln(a[1]);
while a[i]<>1000 do begin
k:=k+a[i];
i:=i+1;
write('vvedi chislo '); readln(a[i]);
end;
i:=i-1;
s:=k/i;
writeln(s);
readkey;
end.