##########################  JAVA - BIGINTEGER #################################
////En implementacion
Variables globales en java
{
    Examples:
    static int phi[] = new int [MAXN + 1];
    static BigInteger K[] = new BigInteger[ 605 ];
    Obs
    - no olvidar el static ya que esta sentencia permite el poder usar la variable desde otro lado del code
    -para el primero como int es un dato primitivo no es necesario crear referencias por cada un de los int creados
    pero para el segundo si es necesario para evitar excepciones
    for( int i = 1 ; i < 604 ; ++i ){
            K[ i ] = BigInteger.ONE;
            K[ i ] = K[ i - 1 ].multiply( kk );
    }
}
Constructores
{
    String s;
    BigInteger num = BigInteger(s);
    int k;
    BigInteger num = BigInteger.valeOf(k);
}

Operaciones aritmeticas
{
    BigInteger ans = BigInteger;
    ans = num.subtract(den);
    ans = num.multiply(den));
    ans = num.add(den);
    ans = num.divide(den);
    REVERSE_MULTIPLIER = BigInteger.valueOf(MULTIPLIER).modInverse(BigInteger.valueOf( mod )).longValue();// modInverse , longValue()
}
Operaciones con Bigdecimal
{
    System.out.printf(Locale.US,"%.10f\n", s);//Para que no se contraiga con la notacion cientifica ejm : 1.8E-10
    .toPlainString();   //Returns a string representation of this BigDecimal without an exponent field.
    stripTrailingZeros()    // Returns a BigDecimal which is numerically equal to this one but with any trailing zeros removed from the representation. ejm 5^2 == 25.00 > 25
}
String en Java
    Acceso a elementos s.charAt(i);
    Tamao s.length();
    Substring en el intervalo [a-b> : s.substring(a, b);
    Substring en el intervalo [a-oo> : s.substring(a);
    //INVESTIGAR s.endsWith("ize") s.startsWith("post")
    ///OJO INVESTIGAR (PARECE s.find )cad.indexOf('+')) != -1
Scanner I/O en JAVA
    Declaracion     Scanner cin = new Scanner(System.in);
    String s = cin.nextLine();// next();
Parsing
    String s;
    int t = Integer.parseInt( s );
Map en JAVA
    Map< String , Integer >M = new HashMap<String, Integer>();

    if( !M.containsKey(temp) )
       M.put(temp, 1 );
    else M.put(temp, M.get(temp) + 1 );
    for (Map.Entry<String, Integer> entry : M.entrySet())
    {
        max = entry.getValue();
        ans = entry.getKey();
    }
Set en java // Array de Set
    TreeSet< obj >[] set = new TreeSet [ ns + 1 ];
    for( int i = 0 ; i <= ns ; ++i ) set[ i ] = new TreeSet< obj >();
Objects en java
    new // siempre usarlo al crear un nuevo objeto ya que a modo practico esta sentencia como que creara espacio fisico en la variable
    Example : set[ 2*k ].add( new obj( H1.hash( i , i + k + 1 ) , i ) );
    Objeto comparador
    public static class obj implements Comparable< obj > {
        long a ;
        int b;

        obj(long a, int b) {
            this.a = a;
            this.b = b;
        }
        public int compareTo( obj o )
        {
            if( o.a != a )return (int)(a - o.a);
            return (int)( cc.charAt( b ) - cc.charAt( o.b ) );
        }
    }
    Tambien se puede hacer este truco //http://codeforces.com/contest/19/submission/86646
    Integer o[] = new Integer[ sz ];
    for( int i = 0 ; i < sz ; ++i ) o[ i ] = i;
    Arrays.sort( o , new Comparator< Integer >() {
        public int compare( Integer o1 , Integer o2 )
        {
            if( H1[ o1 ] != H1[ o2 ] ) return (int)( H1[ o2 ] - H1[ o1 ] );
            return (int)( H2[ o2 ] - H2[ o1 ] );
        }
    });
    /*http://codeforces.com/contest/19/submission/86646
Integer o[] = new Integer[ sz ];
for( int i = 0 ; i < sz ; ++i ) o[ i ] = i;
Arrays.sort( o , new Comparator< Integer >() {
    public int compare( Integer o1 , Integer o2 )
    {
        if( H1[ o1 ] != H1[ o2 ] ) return (int)( H1[ o2 ] - H1[ o1 ] );
        return (int)( H2[ o2 ] - H2[ o1 ] );
    }
});
*/
// StringHash taked of EgorK , http://codeforces.com/contest/113/submission/676303
// Pendiente arraylist y otros coleccions
// Sorting array  Arrays.sort( A , 0 , n - 1 ); creo xd
// Freopen in java
static private final String input = "derangements.in";
    static private final String output = "derangements.out";

    public static void main(String[] args)throws FileNotFoundException {
        Scanner cin = new Scanner(new File(input));
        int n = cin.nextInt();
        cin.close();
        int ans = f( n );
        PrintWriter s=new PrintWriter(output);
        s.println( ans );
        s.close();
    }
//
public int compareTo(BigInteger val)
Parameters
val - BigInteger to which this BigInteger is to be compared

Return Value
This method returns -1, 0 or 1 as this BigInteger is numerically less than, equal to, or greater than val.

//
Nextpermutation in JAVA
int[] nextperm(int[] vals) {
   int i =  vals.length-1;
   while (true) {
      int ii =  i;
      i--;
      if (vals[i] < vals[ii]) {
         int j = vals.length;
         while (vals[i] >= vals[--j]);
            int temp = vals[i];  //Swap
            vals[i] = vals[j];
            vals[j] = temp;
         int begin = ii, end = vals.length-1;
         while (end>begin) {
               int stemp = vals[end];   //Swap
               vals[end] = vals[begin];
               vals[begin] = stemp;
            end--; begin++;
         }
         return vals;
      } else if (vals[i] == vals[0]) {
         int begin = 0, end = vals.length-1;
         while (end>begin) {
               int stemp = vals[end];   //Swap
               vals[end] = vals[begin];
               vals[begin] = stemp;
            end--; begin++;
         }
         return vals;
      }
   }
}