program zadatakkkk;
var i,znak:integer; a,b,ai:real;
begin
        readln(a,b);
        i:=0;
        ai:=0;
        znak:=1;

        repeat
                i:=i+1;
                znak:=-znak;
                ai:=ai+1/i;
        until (znak*ai<a) OR (znak*ai>b) OR (i=100);

        writeln(ai:6:2);
end.

Program zad2;
var n,stepen, ostatak:integer; bin:longint;
begin
  readln(n);
  
  stepen:=1;
  
  while(n>0) do
  begin
   ostatak:=n mod 2;
   n:=n div 2;
   bin:=bin + stepen*ostatak;
   stepen:=stepen*10;
  end;
  
  writeln(bin);
end.

program p123;
var n,br,br1,a,stepen:integer;
begin
read(n);
stepen:=1;
br:=0;
br1:=0;
 repeat
  a:=n mod 10;
  n:=n div 10;
   if a mod 2 <>0 then
    begin
     br:=br*10+a;
     br1:=br1+stepen*a;
     stepen:=stepen*10;
    end;
   until n=0;
writeln(br,'     ',br1);
end.

Program zad4;
var fib1, fib2, ftrenutno, suma,n,i:integer;
begin
  readln(n);
  fib1:=1;
  fib2:=1;
  suma:=2;
  if (n=1) then writeln('n-ti element je ',1,' dok je suma elemenata isto ',1)
  else if(n=2) then writeln('n-ti element je ',1,' dok je suma elemenata ',2)
  else
  begin
    for i:=3 to n do
    begin
      ftrenutno:=fib1 + fib2;
      suma:=suma + ftrenutno;
      fib1:=fib2;
      fib2:=ftrenutno;
    end;
    writeln('n-ti element je ',ftrenutno,' dok je suma elemenata ',suma);
  end;
end.

program zad6;
var n,i,br,a:integer;
begin
read(n);
br:=0;
for i:=1 to n do
begin
 readln(a);
 if a=0 then br:=br+1;
 if (a<>0) and (br=1) then br:=0;
 if ((a<>0) and (br>1)) or ((br>0) and (a=0) and (i=n)) then
  begin
  writeln(br,'nula');
  br:=0;
  end;
  end;
 end.
 
 Program zad7;
  var n,i,a,b,s,p:integer;
Begin
  read(n);
  read(a);
s:=1;
  for i:=1 to n-1 do
  begin
    read(b);
    p:=p+1;
    if b>a then s:=s+1;
    if (b<a)and(s>1)then
    begin
      writeln('ima ',s,' rastucih brojeva');
      s:=1;
    end;
   if (p=n-1)and(s>1)then writeln('ima ',s,' rastucih brojeva');
   a:=b;
  end;
End.

program p6;
var max,n,i,br,x:integer;
begin
readln(n);
readln(x);
max:=x;
br:=1;
for i:=2 to n do
begin
  readln(x);
  if (max<=x) then 
  begin
    max:=x;
    br:=i;
  end;
end;
writeln(max,' ',br);
end.

program p10;
var n,i,p,t,maxt,post,max,pos : integer;
begin
maxt:=0;
max:=0;
pos:=1;
readln(n);
readln(p);
For i:= 1 to (n-1) do
 begin
 readln(t);
 If t>p then
  begin
  If maxt=0 then
   post:=i;
  maxt:=maxt+1;
  end
   else
    If maxt>0 then
     begin
     If maxt>max then
      begin
      max:=maxt;
      pos:=post;
      end;
     maxt:=0;
     end;
 p:=t;
 end;
If maxt>max then
 begin
 max:=maxt;
 pos:=post;
 end;
writeln(pos,' ',max+1);
end.

Program p11;
var f : boolean;
l,lt,i,j : integer;
txt,w : string;
begin
readln(txt);
readln(w);
l:=0;
While ord(w[l+1]) <> 0 do
l:=l+1;
lt:=0;
While ord(txt[lt+1]) <> 0 do
lt:=lt+1;
f:=false;
For i:= 1 to (lt-l+1) do
 begin
 for j:= i to (i+l-1) do
  begin
  If txt[j]<>w[j-i+1] then
   break;
  If j=i+l-1 then
   f:=true;
  end;
 if f then
  break;
 end;
If f then
 writeln('Rec ',w,' se pojavljuje u unetom teksu.')
  else
   writeln('Rec ',w,' se ne pojavljuje u unetom teksu.');
end.