Program HOC24;
const fi='doc.txt'
fo='ghi.txt'
var a,b,c: integer;
f: text;
procedure ip;
begin
assign(f,fi);
reset(f);
read(f,a,b,c);
close(f);
end;
procedure out;
begin
assign(f,fo);
rewrite(f);
write(f,(a+b+c)/3:2:2);
close(f);
end;
begin
ip;
out;
end.