SCOI2009生日快乐

uses math;
var x,y:extended;
n:longint;
function find(x,y:extended;z:longint):extended;
var i:longint;
r1,r2:extended;
begin
find:=10000000;
if z=1 then
begin
if x>y then exit(x/y) else exit(y/x);
end;
for i:=1 to z-1 do
begin
r1:=find(x*i/z,y,i);r2:=find(x*(z-i)/z,y,z-i);
find:=min(find,max(r1,r2));
end;
for i:=1 to z-1 do
begin
r1:=find(x,y*i/z,i);r2:=find(x,y*(z-i)/z,z-i);
find:=min(find,max(r1,r2));
end;
end;
begin
readln(x,y,n);
writeln(find(x,y,n):0:6);
end.