Program Pr1;
uses crt;
var mas:array[1..40] of integer;
i:integer;
v:real;
Begin
clrscr;
v:=0;
randomize;
for i:=1 to 40 do mas[i]:=random(21);
for i:=1 to 40 do v:=v+mas[i];
v:=v/40;
writeln(v);
end.