//---------------------------------------------------------------------------
// Miranda Moore
// COS488/MAT474
// Problem Set 9, Q2
//---------------------------------------------------------------------------
// The command "java Permutation N"
// returns the number of permutations of N atoms that have no 1- or 2-cycles.
// 
// Examples:
//    > java Permutation 3
//    2
//    > java Permutation 4
//    6
//    > java Permutation 5
//    24
//    > java Permutation 6
//    160
//---------------------------------------------------------------------------


public class Permutation { 
      
    
    // Counts the number of pemutations of N atoms having no 1- or 2-cycles
    private static long count(int N, long[] fact) {
           
        long count = 0;
        
        if (N == 0)
            count = 1;    // necessary base case
        else if (N == 1 || N == 2) 
            count = 0;
        else {
            // All the possibilities for a cycle of size >= 3 
            // containing the atom of largest index
            for (int k = 2; k <= N-1; k++) {
                count += (fact[N-1]/fact[N-k-1] * count(N-k-1, fact));
            }
        }
        
        return count;        
    }
    
    
    public static void main(String[] args) {
        int N = Integer.parseInt(args[0]);
        
        // Compute array of all the factorials
        long[] fact = new long[N+1];
        fact[0] = 1;
        for (int i = 1; i <= N; i++) {
            fact[i] = i*fact[i-1];
        }
        
        System.out.println(count(N, fact));
    }
}