read(x,y);
readln(e);
t:=0;
if ((abs (x-sin(sqrt(t)))<=e) and (abs(y-cos(t))<=e))
 then begin  write('0') ; exit; end;
f1:=true;

f2:=true;

repeat
t:=t+e
until (abs(sin(sqrt(t))-x)<=e) and (abs(cos(t)-y)<=e)  or (t>10e12) ;

if t>10e12 then write ('FAIL') else write(t:0:1);