program p;
var a,b,c:real;
fucntion max(a,b:real):real;
begin
if a>b then max:=a else max:=b;
end;
begin
readln(a,b,c);
writeln((max(a,a+b)+max(a,b+c))/(1+max(a+bc,15)));
end.
program p;
var a,b,c:real;
fucntion max(a,b:real):real;
begin
if a>b then max:=a else max:=b;
end;
begin
readln(a,b,c);
writeln((max(a,a+b)+max(a,b+c))/(1+max(a+bc,15)));
end.