function mm(x,y,z:real):real; var f:real; begin if (x>y) and (x>z) then f:=x else if (y>x) and (y>z) then f:=y else if (z>x) and (z>y) then f:=z; mm:=f; end;
var x,y,z,m:real; begin readln(x); readln(y); readln(z); m:=mm(x,y,z)/-mm(-(x-y),-(x-z),-(y-z)); writeln(m); end.
function mm(x,y,z:real):real;
var
f:real;
begin
if (x>y) and (x>z) then
f:=x
else if (y>x) and (y>z) then
f:=y
else if (z>x) and (z>y) then
f:=z;
mm:=f;
end;
var
x,y,z,m:real;
begin
readln(x);
readln(y);
readln(z);
m:=mm(x,y,z)/-mm(-(x-y),-(x-z),-(y-z));
writeln(m);
end.