uses crt;
var a,b,c,cc,s:integer;
begin
cc:=0;
readln(a);
if a>0 then begin s:=a; inc(cc); end;
readln(b);
if b>0 then begin s:=s+b; inc(cc); end;
readln(c);
if c>0 then begin s:=s+c; inc(cc); end;

writeln(s/cc);
readln;

end.

var a,b,c,s,k:integer;
begin
readln(a,b,c);
if a>0 then
begin
k:=k+1;
s:=s+a;
end;
if b>0 then
begin
k:=k+1;
s:=s+b;
end;
if c>0 then
begin
k:=k+1;
s:=s+c;
end;
if k=0 then writeln('нет положительных чисел')
else writeln(s/k);
end.