program unsprezece;
var i,q,p,k:integer;
    s,r:longint;
    e:real;
function putere(a,b:integer):longint;
begin
if b=0 then putere:=1
else putere:=a*putere(a,b-1);
end;
begin
write('p=');
readln(p);
write('q=');
readln(q);
write('k=');
readln(k);
s:=0;
for i:=1 to k do s:=s+putere(p,i);
r:=1;
for i:=1 to k do r:=r*putere(q,i);
e:=s/r;
writeln(e:5:2);
readln;
end.