program Project1;

{$APPTYPE CONSOLE}

{$APPTYPE CONSOLE}
 var  d,a,b:real;
 f1,f2:text;
 begin
 assign(f1, 'input.dat');
 reset(f1);
 readln (f1,a);
 readln (f1,b);
 close (f1);
 d:=b/2;
 assign (f2, 'output.sol');
 rewrite (f2);
 writeln(f2,d);
 close (f2);
 end.