var
a,b,n,m:integer;
begin
write('a,b,n,m: '); readln(a,b,n,m);
writeln(exp(n*ln(a+b))/(1+a/(exp(m*ln(a))-exp((m-n)*ln(b;
end.
var
a,b,n,m:integer;
begin
write('a,b,n,m: '); readln(a,b,n,m);
writeln(exp(n*ln(a+b))/(1+a/(exp(m*ln(a))-exp((m-n)*ln(b;
end.