program a9(input,output);
var t,b:integer; a,x,p:real;
begin
readln(a,t,b,x);
p:=(ln(abs(((2*a)+sqr(x))/(a-sqr(x)))))+((exp((ln(t-sqr(a)))/3))/(sqrt(abs(t-sqr(b)))));
writeln(p);
end.
program a22(input,output);
var z,x1,x2,x3:real;
begin
readln(x1,x2,x3);
if exp(x3)>30 then z:=exp((ln(abs(1+x1)))/5)
else if exp(x3)<30 then z:=cos(3.1415927*41/180)
else if exp(x3)=30 then z:=12.41-ln(abs(x2));
writeln(z);
end.