const fi='data.txt'
fo='tbc.txt'
var f1,f2:text;
a:array[1..100]of integer;
n,i,t:integer;
begin
assign(f1,fi); reset(f1);
assign(f2,fo); rewrite(f2);
n:=0;
while not eof(f1) do
begin
n:=n+1;
readln(f1,a[n]);
end;
t:=0;
for i:=1 to n do
t:=t+a[i];
writeln(f2,t/n:4:2);
close(f1);
close(f2);
end.