program sapch;
uses
crt;
var
k, s, c: integer;
sr: real;
begin
s := 0;
c := 0;
k := 1;
while k <> 0 do
readln(k);
s := s + k;
c := c + 1;
end;
writeln;
sr := s / c;
writeln(sr);
readln;
end.
program sapch;
uses
crt;
var
k, s, c: integer;
var
sr: real;
begin
s := 0;
c := 0;
k := 1;
while k <> 0 do
begin
readln(k);
s := s + k;
c := c + 1;
end;
writeln;
sr := s / c;
writeln(sr);
readln;
end.