var x, y: real;
begin
readln(x);
if x = 0 then
writeln('На ноль делить нельзя!')
else begin
y := 1 / x;
writeln('1/'+x+'='+y);
end;
end.
==============================
program task;
var
x, f: real;
begin
readln(x);
if (x > 2) and (x < 5) then
f := 2 * x
else f := 0;
write(f);
end.